(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Properties of petroleum oils in relation to performance as citrus tree sprays in Florida"

PROPERTIES OF PETROLEUM OILS 

IN RELATION TO PERFORMANCE AS 

CITRUS TREE SPRAYS IN FLORIDA 



KENNETH TRAMMEL 



A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF 

THE UNIVERSITY OF FLORIDA 

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE 

DEGREE OF DOCTOR OF PHILOSOPHY 



UNIVERSITY OF FLORIDA 

April, 1965 



ACKNOWLEDGMENTS ■ ' • :. 

The author expresses sincere appreciation to Dr . J, T. Creighton 
for serving as chairman of his supervisory committee and for financial 
aid obtained through a National Defense Education Act fellowship. He 
is deeply indebted to Dr. W. A. Simanton, co-chairman, for supervision 
and assistance during the course of the investigations, for obtaining 
grant funds to support the investigations, and for his invaluable 
guidance in preparation of the manuscript. Appreciation is extended 
to Dr. A. H. Krezdorn, Dr. Milledge Murphey, and Dr. V. G. Perry for 
serving on the supervisory committee and for critically reviewing the 
manuscript. 

He is grateful to Dr. H. J. Reitz for financial aid and for use of 
the facilities at the Citrus Experiment Station, and to numerous staff 
members of the Citrus Experiment Station for consultation, advice, and 
use of their laboratory facilities. Appreciation is expressed to Mrs. 
Harriet Long of the Citrus Experiment Station for taking the photo- 
graphs. The assistance of Mr , B. G. Shively in conducting the experi- 
ments, especially his willingness to work long hours at night and on 
week ends, is greatly appreciated. 

Gratitude is expressed to the personnel of Humble Oil and Refining 
Company, especially Mr. R. C. Halter, for the grant which supported the 
investigations and for numerous oil samples used in this work. Contri- 
bution of samples by the following oil companies is acknowledged: Gulf 
Oil Corporation; Sun Oil Company; Shell Oil Company; Texaco, Incorpo- 
rated; and American Oil Company. Contribution of emulsifiers by the 

'■ li 



Rohm and Haas Company is appreciated. 

The author expresses special appreciation to his wife for her 
understanding, encouragement, and support during the years of study 
prior to the preparation of the manuscript, and for her cooperation 
and assistance in preparation of the manuscript. 

He wishes to thank Mrs. Cynthia Boyd Evans for performing the 
final typing and assisting in the Multilith duplication of the 
manuscript. 



Ill 



TABLE OF CONTENTS 

Page 

ACKNOWLEDGMENTS ii 

LIST OF TABLES vi 

LIST OF FIGURES viii 

INTRODUCTION 1 

LITERATURE REVIEW 3 

Source and Properties of Petroleum Spray Oil 3 

Historical Use of Spray Oil 5 

Insecticidal and Ovicidal Action of Petroleum Oil 7 

Phytotoxicity of Petroleum Oil 12 

Penetration of oil into plants 12 

Effects of oil on the physiological processes of plants 14 

Injurious effects of oil sprays on citrus 17 

Specifications for Plant Spray Oils 19 

MATERIALS AND METHODS 23 

Oil Specifications , , , 23 

Preparation of Oils 27 

Application of Oils in Laboratory Studies 27 

Oil Deposit Determination 32 

Insecticidal and Ovicidal Efficiency Studies 34 



Florida red scale studies, 



34 



Infestation , 34 

Holding infested fruit „ 35 

Scale development, treatment, and mortality counts 38 

Testing the oils 40 

Citrus red mite studies , ^ 41 

Phytotoxicity Studies 43 

Laboratory experiments 43 

Respiration studies 43 

Transpiration study 45 

Field experiments 4g 



iv 



Page 

Field Experiment No. 1: oil blotch, leaf drop, and 

fruit drop 47 

Field Experiment No. 2: fruit color and internal fruit 

quality 47 

Color measurement and ethylene degreening 48 

Fruit quality 49 

RESULTS AND DISCUSSION 50 

Relation of Composition and Heaviness of Oils to Insecticidal 

and Ovicidal Efficiency 50 

Results 50 

Florida red scale studies 50 

Citrus red mite studies 61 

Discussion 71 

Relation of Composition, Heaviness, and Refinement of Oil to 

Phytotoxicity 77 

Respiration and transpiration 77 

Results 77 

Discussion 84 

Oil blotch, leaf drop, and fruit drop 88 

Results 88 

Discussion 92 

Fruit color and ethylene degreening 96 

Results 96 

Discussion 99 

Internal fruit quality 106 

Results 106 

Discussion 109 

General Discussion 112 

SUMMARY AND CONCLUSIONS 115 

LITERATURE CITED 121 

ADDITIONAL REFERENCES 130 

BIOGRAPHICAL SKETCH 131 



LIST OF TABLES 

Table Page 

1 Specifications for California spray oils 20 

2 Specifications for oils applied to fruit and shade trees 

in New York , 22 

3 Specifications for various properties of petroleum oils 

used in these studies 24 

4 Oil deposit, number of scales, and per cent kill with 3 
series of petroleum oils in dosage-mortality tests against 
Florida red scale 51 

5 Effectiveness of 3 series of petroleum oils against adult 
female Florida red scale 53 

6 Effectiveness of commercial oils at 2 levels of appli- 
cation against adult female Florida red scale 59 

7 Oil deposit, number of eggs, and per cent kill with 3 
series of petroleum oils in dosage-mortality tests 

against citrus red mite eggs 62 

8 Effectiveness of 3 series of petroleum oils against 

citrus red mite eggs 65 

9 Spider mite counts at 1, 4, and 7 weeks after application 

of spray oils on 6 May 1964 in Block 23 72 

10 Respiratory rates of oil-sprayed 'Pineapple' seedlings 
expressed as per cent of the check. Each value is the 
mean of 6 determinations. Oils were applied at 70 to 80 
Mg/cm^ 78 

11 Effect of 365-mol wt paraffinic oil on respiration of 
adjacent treated and untreated leaves of 'Pineapple' 
seedlings, measured as O2 uptake in |ig/cm^ leaf surface 
in a 2-hour period. The oil deposit was high 

(154.4 M.g/cm2) 79 

12 Transpiration rate of 'Pineapple' seedlings sprayed with 
1.57o concentration of low, medium, and high molecular 

weight fractions of paraffinic and naphthenic oils 80 



vl 



Table Page 

13 Leaf drop by young 'Hamlin' trees following application 

of oil sprays on 6 May 1964 in Block 23 89 

14 Fruit drop by young 'Hamlin' trees following application 

of oil sprays on 6 May 1964 in Block 23 93 

15 Color of oil- sprayed 'Hamlin' oranges before and after 
different intervals of ethylene degreening and per cent 
pack-out at 4 and 8 weeks after spraying 97 

16 Regression equations for the degreening rate of oil- 
sprayed 'Hamlin' oranges and hours required to degreen 

to 30% absorbance level 100 

17 Analysis of oil- sprayed 'Hamlin' oranges at 4 dates of 
harvest. Each mean is the average of determinations on 

four 40- fruit samples. Sprayed 18 September 1964 107 



vii 



LIST OF FIGURES 



Figure Page 

1 Laboratory air-blast sprayer. A, high velocity blower; 
B, motor; C, pump; D, spray tank; E, pressure regulator; 
F, nozzle; G, deflector vanes; H, operating lever; I, 
turntable 29 

2 Spray coverage obtained on fruit with the laboratory air- 
blast sprayer. A, fruit sprayed with oil at 1.0% concen- 
tration containing fluorescent dye to show the distribu- 
tion of the oil; B, unsprayed fruit. Photographed under 
ultra-violet light. The rectangular area on fruit "A" 
was left unsprayed to show the contrast between sprayed 

and unsprayed surface 31 

3 Method of infesting grapefruit with Florida red scale for 
laboratory studies. A, ivy leaves with natural infesta- 
tion of crawler-producing female scales; B, cheesecloth 
strip with infested leaf sections; C, strip of leaf 
sections wrapped firmly in position around the equator 

of a grapefruit to allow crawlers to transfer; D, typical 
infestation obtained by this method, at time of treatment 
application (4.5 weeks after infestation) 35 

4 Scale- infested grapefruit on moist vermiculite in holding 

tray 37 

5 Holding facilities for infested fruit in laboratory 
studies. A, chamber for holding trays of scale-infested 
grapefruit; B, racks supporting immature oranges in- 
fested with citrus red mite eggs 39 

6 Regression of per cent kill on deposit level for 3 series 
of narrow-boiling petroleum fractions tested against adult 
female Florida red scale. The number on each line indi- 
cates the average molecular weight of the fraction 54 

7 Efficiency in relation to molecular weight for 3 series of 
narrow-boiling petroleum fractions against adult female 
Florida red scale 55 

8 Efficiency in relation to viscosity for 3 series of narrow- 
boiling petroleum fractions against adult female Florida 

red scale 5g 



viii 



Figure Page 

9 Efficiency in relation to 50% distillation point for 3 
series of narrow-boiling petroleum fractions against 
adult female Florida red scale 57 

10 Regression of per cent kill on deposit level for 3 series 
of narrow-boiling petroleum fractions tested against citrus 
red mite eggs. The number on each line indicates the 
average molecular weight of the fraction. The solid por- 
tion of each line indicates the range of data collected; 
the broken extension is extrapolation to the 50 or 95% 

kill level „ 67 

11 Efficiency in relation to molecular weight for 3 series of 
narrow-boiling petroleum fractions and 2 commercial oils 
against citrus red mite eggs 68 

12 Efficiency in relation to viscosity for 3 series of narrow- 
boiling petroleum fractions and 2 commercial oils against 
citrus red mite eggs 69 

13 Efficiency in relation to 50% distillation point for 3 
series of narrow-boiling petroleum fractions and 2 
commercial oils against citrus red mite eggs 70 

14 Effect of light, medium, and heavy paraffinic fractions 
on the transpiration rate of treated 'Pineapple' orange 
seedlings in relation to time after treatment. Shaded 
symbols indicate significance from check 82 

15 Effect of light, medium, and heavy naphthenic fractions 
on the transpiration rate of treated 'Pineapple' orange 
seedlings in relation to time after treatment. Shaded 
symbols indicate significance from the check 83 

16 Accumulated leaf drop from 'Hamlin' orange trees in the 
5-week period following application of 4 oils on 6 May 

1964 „ . . , 91 

17 Degreening rate of oil- sprayed 'Hamlin' oranges 4 weeks 
after spraying as indicated by decrease in per cent 
absorbance with time in ethylene degreening chamber. 
Sprays applied 18 September 1964; fruit harvested 16 

October 1964 . , 101 

18 Degreening rate of oil-sprayed 'Hamlin' oranges 8 weeks 
after spraying, as indicated by decrease in per cent 
absorbance with time in ethylene degreening chamber. 
Sprays applied 18 September 1964; fruit harvested 12 
November 1964 102 



Ix 



Figure Page 

19 'Hamlin' oranges from plots receiving late-season appli- 
cation of 4 oils and degreened for 0, 24, 48, and 72 
hours; sampled 4 and 8 weeks after treatment. Sprays 
applied 18 September 1964 105 

20 Effect of 4 oils on soluble solids development in 'Hamlin' 
oranges. Sprays applied 18 September 1964 108 



INTRODUCTION 

Petroleum oil is one of the most important pesticides used on 
Florida citrus. It will control most species of scale insects, spider 
mites, and the fungus disease greasy spot, caused by Cercospora citri - 
grisea Fisher. Compared to most chemical pesticides, oil is economical 
and safe for the user, has little adverse effect on biological control 
agents, and its use creates no pesticidal residue problem. Because of 
the physical mode of action of oil, development of resistance by the 
above pests is unlikely. However, the use of oil is limited to a 
short application period in June and July because of its adverse ef- 
fects on the citrus plant. Improper application of oil sprays may re- 
sult in fruit blemishes, excessive leaf and fruit drop, reduced fruit 
set, poor fruit color and quality, and increased susceptibility of the 
tree to cold weather injury. 

Foliage- type spray oils are characterized by the physical proper- 
ties of viscosity, distillation range, and molecular weight, and the 
chemical properties of unsulfonated residue, or refinement, and hydro- 
carbon composition. There are no recommended specifications for these 
properties for oils used in Florida at present and a wide range of 
materials are currently in use. Specifications for oils used on citrus 
in California and on deciduous fruits in New York are well defined. In 
recent years, some major oil companies have used specifications from 
these states as guides in producing base oils for use on Florida cit- 
rus, mainly because no information was available to indicate different 



requirements. Although the available oils are quite diverse in their 
properties, their use by Florida citrus growers over the past few years 
has not generally resulted in excessive damage. However, damage from 
oil sprays is not uncommon even though it is not always striking. 
Where problems do occur, information about oil properties, formulation, 
and application, sufficient to establish a probable cause, is seldom 
available. Information pertaining to the relationship between chemical 
and physical properties of spray oils and performance on Florida citrus 
is needed. 

The objective of the work reported herein was to establish the re- 
lationship of physical and chemical properties of petroleum oil to in- 
secticidal and ovicidal efficiency, and to phytotoxicity to citrus, 
under Florida conditions. Three series of narrow-distillation range, 
experimental fractions and numerous commercial oils provided wide 
ranges of the various properties for study. The oils were tested in 
the laboratory against adult female Florida red scale, Chrysomphalus 
aonidum (L,), and against eggs of the citrus red mite, Panonychus citri 
(McGregor), to establish the effective ranges of the various properties 
for insecticidal and ovicidal efficiency. Phytotoxicity studies were 
conducted under both laboratory and field conditions to relate oil 
heaviness, refinement, and chemical composition to various adverse 
effects on citrus. The results obtained may serve as a guide for ad- 
ditional field studies, leading eventually to more rigid specifications 
for petroleum oils used on citrus in Florida. 



LITERATURE REVIEW 

Source and Properties of Petroleum Spray Oil 
Petroleum or "rock oil" (Greek petros = rock, and oleum = oil) is 
mainly an oily liquid mixture of numerous hydrocarbons believed to have 
been formed from the remains of animal and vegetable marine organisms. 
It is comprised chiefly of paraffins (aliphatic chains), naphthenes or 
asphaltics (saturated ring hydrocarbons), aromatics (ring hydrocarbons 
with conjugated double bonds), and unsaturates (aliphatic or cyclic 
hydrocarbons with one or more active double or triple bonds). The oil- 
producing areas or fields in the United States are regionally referred 
to as Eastern, Mid-continent, and Western or Californian. The Eastern 
fields produce predominantly paraffin-base crudes, the Californian 
fields produce predominantly asphaltic- or naphthenic-base crudes, and 
the Mid-continent fields produce crudes of a mixed-base type. However, 
any one of these types may be produced by individual wells in any area 
(24) . 

In the distillation of a crude, the various petroleum fractions 
come off in the order of liquified gas, petroleum ether, gasoline, 
naphtha, kerosene, fuel oil, mineral seal oil, transformer oil, summer 
spray oil, dormant spray oil, and lubricating oil. The summer and 
dormant spray oils are in the light lubricating range. The heavier 
materials withdrawn from the bottom of the fractionating tower, called 
the residuum, may be used as fuel or, if from a suitable crude, re- 
worked into asphalt. Distillation of the fractions from transformer 



oil on up is conducted under vacuum to avoid heating above 750 F, at 
which temperature decomposition, or cracking, occurs (24). 

After distillation, the various cuts must be refined to remove un- 
desirable substances. Kerosene, spray oils, and lubricating oils are 
refined by essentially the same methods. The once common sulfuric acid 
treatment has given way in recent years to a process employing sulfur 
dioxide, known as the Edeleanu process. The oil and sulfur dioxide gas 
are mixed in a pressure system and cooled to obtain 2 layers: 1) the 
extract (lower layer), containing aromatic and other unsaturated hydro- 
carbons dissolved in the liquid sulfur dioxide; and 2) the raffinate 
(upper layer), consisting of sulfur dioxide dissolved in the remaining 
hydrocarbons. The raffinate yields the refined oil and the extract 
becomes a source of industrial solvents. The sulfuric acid process 
functions chemically while the sulfur dioxide method is a physical 
process, its action being that of solvent extraction. Other solvent 
extraction processes are now in use: nitrobenzene, Chlorax, phenol, 
furfural, and Duosol. Spray oils require further refinement with sul- 
furic acid after the usual treatment given the lubricating oils. The 
oil is treated with hot sulfuric acid which has the combined properties 
of strong acid, drying agent, and oxidizing agent. Hence, the sul- 
fonation process removes all but the most inert substances. The com- 
pounds removed are: 1) unsaturated hydrocarbons (both straight chain 
and aromatic); 2) oxygen compounds (e.g., phenols and naphthenic acids); 
3) sulfur compounds (e.g., mercaptans, pentamethylene sulfides, and 
thiophene); and 4) nitrogen compounds (e.g., quinoline) . That part of 
the oil not reacting with the sulfuric acid, the saturated hydrocarbons, 
is known as the unsulfonated residue, or UR. Hence the UR of an oil is 



in direct relationship to its degree of refinement (25). 

The most important properties used for defining spray oils are 
those which indicate "heaviness" or volatility, refinement, and hydro- 
carbon composition. Viscosity (seconds Saybolt Universal = SSU) and 
molecular weight are measures of the heaviness of oils but are valid 
only for comparing oils of the same composition. Distillation temper- 
atures are most directly related to volatility and may be used to com- 
pare oils of varying hydrocarbon composition. Oil refinement is indi- 
cated by the per cent unsulfonated residue as explained above and is 
especially important in relation to plant safety. Hydrocarbon compo- 
sition refers to the relative content of paraffinic and naphthenic com- 
pounds, since both types are present in spray oils (9, 24, 25). Gener- 
ally speaking, paraffinic oils contain approximately 65 to 75% paraf- 
finic carbons and naphthenic oils contain about 45 to 55% naphthenic 
carbons. 

Historical Use of Spray Oil 
The insecticidal efficiency of petroleum oil was recognized nearly 
a century ago, as undiluted kerosene was applied directly to insect- 
infested trees around 1870 (72). Kerosene, soap, and water mixtures 
were recommended during the 1870 's and the Riley- Hubbard formula for a 
kerosene, whale-oil soap, and water emulsion was published in 1883 (72). 
Hubbard (35) recognized kerosene as the most effective insecticide for 
combating scale insects on citrus in Florida in 1885. The kerosene- 
soap emulsion remained a standard insecticide for use on citrus both in 
Florida and California for many years. In addition to kerosene, crudes 
and distillates were also tried with varying degrees of success (72). 



Yothers (103) introduced lubricating oils about 1911 and these 
gradually came into wide use in controlling scale insects and white- 
flies on citrus in Florida. 

The interest in oil sprays declined somewhat during the years 1910 
to 1920, especially in California, in favor of lime- sulfur spray and 
HCN gas. However, after a few years, interest in oil sprays was 
revived, but this time to lubricating-oil emulsions instead of the 
older kerosenes, crudes, and distillates. This renewed interest was 
due mainly to the alarming increase in damage caused by the San Jose 
scale, Aspidiotus perniciosus Comstock, to deciduous fruit trees and 
the development of resistance to HCN gas by the California red scale, 
Aonidiella aurantii (Maskell), and the black scale, Saissetia oleae 
(Bernard), (72). 

The interest in oil emulsion sprays was greatly stimulated about 
1925 by the publicity given to the formulae of Yothers (106) and 
Burroughs (3) for boiled lubricating oil emulsions and cold engine oil 
emulsions. These formulae, and the method of emulsif ication, were 
essentially the same as those suggested by Hubbard (35) in the early 
1880' s, except that lubricating oil was specified instead of kerosene, 
crude oil, and distillates. 

Renewed interest in oil sprays stimulated research in all phases 
of the subject--insecticidal, miticidal, and phytocidal. The main 
problem with petroleum oil was that of phytotoxicity . Hence the bulk 
of the research since the early 1920 's has been concerned with the 
phytotoxic properties of oils, and with the development, through re- 
finement and other means, of oils less detrimental to plants. Con- 
current with this, the insecticidal properties were studied in order to 



maintain high insecticidal efficiency of oil while reducing its degree 
of phytotoxicity. 

Since the early work of Hubbard and Yothers in Florida, research 
workers in many areas of the country, particularly in Florida 
(Thompson), California (DeOng, Smith, Knight, Chamberlin, Ebeling, 
Wedding, Riehl, and others), and New York (Pearce, Chapman, and Smith), 
have expended considerable time and effort in spray oil research. 

Insecticidal and Ovicidal Action of Petroleum Oil 
DeOng et al . (19) attributed the insecticidal action of unrefined 
petroleum oil to suffocation and toxic action, the latter due chiefly 
to the action of unsaturated hydrocarbons and the former due to non- 
volatility or film-permanence. They stated that the wax solubility of 
oil determined to a great extent the insecticidal effectiveness of 
lubricating oils against the California red scale. The oils dissolve 
the waxy coating of the insect and penetrate to the spiracles, thus 
halting the respiratory process. DeOng (18) had earlier found that 
scales could expell the highly refined volatile oils, e.g., kerosene, 
from the tracheal system, thus rendering these materials ineffective. 
But any volatile oil containing a large amount of unsaturated hydro- 
carbons seemed to pass throughout the body cavity, dissolving first the 
fat bodies and finally even the entire cellular structure of the in- 
terior part of the body. Non-volatile oils could not be expelled from 
the spiracles by the insects. 

Swingle and Snapp (81) cited reports that oil did not affect 
respiration of insects, and also that it was not suffocation which 
killed the insect but rather the gases given off by the oil after 
entering the tracheal system. These views are in conflict with the 



8 

results obtained by other authors reporting on the subject. 

Nelson (40) reported that kerosene penetrated throughout the tra- 
cheal system and eventually into muscles and nerve ganglia. Woglum 
(101) and Woglum and LaFollette (102) found that the residual oil film 
killed scale crawlers through inhibition of settling and concluded that 
this was an important means by which oil controlled California red 
scale. 

Smith (73) pointed out that in many instances the oil does not 
reach the tracheal system of scale insects, in which case, "...if the 
insect succumbs, death is apparently caused by a prolonged impairment 
of physiological processes such as might be induced by the presence of 
the oil film in the scale covering or in contact with the derm of the 
insect's body." 

Ebeling (22) corroborated the reports of Woglum (101) and Woglum 
and LaFollette (102) concerning inhibition of settling of scale 
crawlers and of Smith (73) as to the effect of oil in the scale cover- 
ing. Ebeling (22) established that crawler settling is inhibited, 
whitecap mortality is high where settling does occur, young stages are 
more easily killed than adults, and tracheal penetration is the chief 
cause of adult mortality but death can occur without it. In addition, 
he found adult scales were much more vulnerable to oil treatments where 
the margins of their armors were loosened from the substratum. The 
scales that survived the treatment gave birth to a high percentage of 
dead embryos and dead crawlers. Scales on the branches of the tree 
were harder to control because of the absorptive nature of the rough 
bark. 



. W""ll;/«. fjr 1^ 



Oil is also an important ovicide. It has proved effective against 

eggs of various insects and mites. Smith and Pearce (70) suggested 

that the mode of ovicidal action of oil may be the prevention of ready 

elimination of toxic metabolites, causing their accumulation in lethal 

amounts. The respiratory rate of eggs of the oriental fruit moth, 

Grapholitha molesta (Busck) , was immediately reduced following oil 

application. They demonstrated that oil must remain on the chorion for 

at least 24 hours to be completely effective. Older eggs were less 

susceptible than younger ones. Smith (71) summarized various theories 

on the mode of ovicidal action of oils: 

"The oil may prevent the normal exchange of gases through the 
outer covering of the egg. 

"The oil may harden the outer covering so as to prevent 
hatching. 

"The oil may interfere with the water balance. 

"The oil may soften or dissolve the outer covering of the 
egg, through interfering with the normal development of 
the embryo. 

"The oil may penetrate the egg and cause coagulation of 
the protoplasm. 

"The oil may penetrate the egg and interfere with enzyme 
or hormone activity. 

"The oil may come in contact with the emerging insect and 
exert its toxic effect upon the delicate integument." 

But he stated that the precise mechanism might vary with different 

species or that several modes of action might operate simultaneously or 

at different stages in the development of the embryo. 

Ebeling (21) showed that the effectiveness of an oil spray against 

citrus pests was related to the heaviness of the oil and the amount of 

oil applied. Chapman et al. (5) also found that control of apple pests 

was in proportion to the amount of oil applied. Pearce et al. (43) 



10 

concluded that structural composition and molecular weight of the oil 
were the basic factors involved in efficiency in insect control. 

The composition and heaviness of petroleum oil in relation to in- 
secticidal and ovicidal efficiency has been studied by several investi- 
gators (6, 15, 23, 42, 43, 44, 47, 48, 49, 55). Pearce et al . (43) 
found that high paraf f inicity and low content of aromatic structures 
were related to kill of eggs of the fruit-tree leaf roller, Archips 
argyrospilus (Walker). Chapman et al . (6) obtained similar results 
with eggs of oriental fruit moth, codling moth, Carpocapsa pomonella 
(L.), and eye-spotted bud moth, Spilonota ocellana (Denis and 
Schif fermUller) . Pearce and Chapman (44) further demonstrated the re- 
lationship between paraf f inicity and efficiency against eggs of 
oriental fruit moth and European red mite, Panonychus ulmi (Koch), and 
against cottony peach scale, Pulvinaria amygdali Cockerell. Efficiency 
also increased with viscosity and molecular weight up to a point. The 
critical value in molecular weight was 320. The maximum efficiency in 
relation to viscosity was obtained at about 50 SSU, 70 SSU, and 90 SSU 
for isoparaff inic, paraffinic, and naphthenic types, respectively. 

Riehl and LaDue (47) found definite correlation of oil viscosity 
and molecular weight to efficiency in control of California red scale 
adults and citrus red mite eggs. They found paraffinic oils superior 
to naphthenic oils and concluded that efficiency of spray oils against 
citrus pests may be considerably improved by proper selection with 
respect to structural character and molecular size. These conclusions 
were strengthened by the work of Riehl and Carmen (48) and Riehl and 
Jeppson (49). Insecticidal efficiency increased with molecular weight 
in the range 220 to 360. Maximum efficiency for highly paraffinic 



.: , 11 

petroleum oils occurred at approximately 340 mol wt (49) . 

Fiori et al. (27) found an inverse relationship between volatility 
of petroleum oils and ovicidal efficiency. Generally, oils fell into 
three distinct groups: 1) ineffective oils, those volatilizing within 
12 hours; 2) moderately effective oils, those volatilizing in 12 to 24 
hours; and 3) highly effective oils, those with little or no volatili- 
zation in 24 hours. Chapman et al . (9) considered volatility, as de- 
termined by distillation, to be the most definitive and useful desig- 
nation for a spray oil. 

Thompson (84, 88), Thompson and Griffiths (86), and Thompson 
et al. (89 J 90) have reported on the effectiveness of oil in controll- 
ing citrus insects in Florida. When timed properly to avoid injury to 
the trees, oil generally has given satisfactory control of purple scale, 
Lepidosaphes beckii (Newman), Florida red scale, and related forms, and 
citrus red mite. The recommended rate for scale control was 1.3%. 

Thompson (84) reported no difference between paraffinic and 
naphthenic oils in controlling purple scale and Florida red scale when 
applied at concentrations of 1.3 to 1.4% oil. However, at a concen- 
tration of 1.0%, paraffinic oil was superior to naphthenic oil. He 
found no correlation between scale control and increase in viscosity in 
the range 72 to 110 SSU. Dean and Bailey (15) reported superiority of 
paraffinic oils and correlation of oil heaviness to efficiency in con- 
trolling Texas citrus mites, Eutetranychus banksi (McGregor). 

Cressman and Dawsey (11) found no relationship between kill of 
camphor scale, Pseudaonidia duplex (Cockerell), and oil refinement in 
a UR range of 67 to 94%. 



12 

Phytotoxicity of Petroleum Oil 

Hubbard (35) reported serious defoliation of citrus plants sprayed 
with kerosene emulsion. Almost every author reporting on oil sprays 
since then has pointed out the phytotoxic hazards of spraying plants 
with petroleum oils. Yothers (104) concluded that all oils apparently 
interfered with the physiological processes of the citrus tree. He 
concluded the oil film interfered with chlorophyll production and noted 
adverse effects of low temperatures following application of oil sprays 
and "blotching" of fruit after an early- season application. 

Gray and DeOng (29) showed a relationship between degree of re- 
finement and phytotoxic effects of petroleum oils. They suggested the 
sulfonation test as a useful guide in judging the safety of an oil. 
DeOng et al . (19) described 2 distinct types of injury to citrus 
foliage by petroleum oils. These were acute and chronic, the former 
being related to light oils and the latter to heavy oils. They ob- 
served defoliation, fruit spotting and dropping, and killing of twigs 
and branches, and noted the apparent interference with transpiration 
and respiration of the plant. Burroughs (4) reported severe leaf burn 
and heavy leaf drop following summer application of oil sprays to apple 
trees . 
Penetration of oil into plants 

DeOng et al . (19) cited Volck (97) as showing that penetration of 
oil into the citrus leaf was most rapid on the abaxial surface, the 
site of the stomatal openings. Knight et al . (36) reported both stoma- 
tal and cuticular absorption of oil by citrus leaves, but penetration 
was not uniform over the entire leaf. Certain focal points were pene- 
trated and the oil spread peripherally from these. Extensive 



13 

translocation of the oil in the citrus plant was reported. However, 
Rohrbaugh (60) studied the fate of the oil film on citrus leaves, 
twigs, and fruit, and found no evidence of translocation or other move- 
ment of oils from leaves into twigs or from small twigs into larger 
twigs, except that oil may migrate short distances between the cells by 
capillarity, and only in cases of heavy applications did it penetrate 
to a depth of more than a few cells beneath the epidermis. 

Oil-soaked areas appear on citrus leaves after spraying with oil. 
This oil eventually migrates internally to an area along the midrib and 
margins of the leaf, resulting in dark discoloration of leaf tissue in 
that area (24) . 

Ginsburg (28) concluded oil penetration into leaves of apple, 
peach, and tomato plants was related inversely to viscosity. McMillan 
and Riedhart (37) reported pure hydrocarbons, having a distillation 
range of 419 to 487 F, penetrated citrus leaves more rapidly than did 
those of a higher boiling range. They concluded that little or no 
cuticular penetration occurred. Young (108) concluded that petroleum 
oil penetration was aided by external forces such as those caused by 
gravitation, capillarity, and bending of tissues by wind. Tucker (94) 
found oil penetration into apricot leaves related to the opening and 
closing of stomata. 

Dallyn and Sweet (12) stated that highly toxic herbicidal oils 
entered the plant indiscriminately from the point of contact and in- 
ternal spread was negligible, while relatively nontoxic oils entered 
largely through the stomata and spread throughout the plant to a con- 
siderable extent. Van Overbeek and Blondeau (96) stated that phyto- 
toxic oils could penetrate only after cells were injured; this was 



14 



accomplished by breaking down of the plasma membrane of the cell by the 
process of solubilization. However, they pointed out that solubiliza- 
tion would not occur with molecules as large as those of foliage spray 
oils. Other workers (10, 13, 39) have studied the penetration and 
phytotoxic action of herbicidal oils. In general, the herbicidal 
activity is related inversely to the heaviness of oil and directly to 
the aromatic hydrocarbon content. However, the petroleum spray oils 
are considerably higher-boiling and more highly-refined than the 
herbicidal oils. The light herbicidal oils are considerably more pene- 
trating than the foliage spray oils. 
Effects of oil on the physiological processes of plants 

Application of oil sprays has resulted in reduced transpiration 
rates of citrus trees (36, 38, 56, 58) and of deciduous fruit trees 
(109) . Merrin (38) reported a 25 to 30% decrease on citrus in Florida, 
with very little difference between first, second, or third- flush 
growth. Knight et al . (36) reported reduction of transpiration of 
citrus by 50-SSU and 106-SSU oils but recovery was faster with the 
light oil. 

Riehl et al . (56) determined the effect of a medium-grade 
California oil on transpiration of several varieties of citrus in the 
laboratory. On the first day after the application of 1.75% oil in 
aqueous mixture, transpiration of the oil- sprayed plants was reduced to 
one- third that of untreated plants. The reduction seemed to be due to 
physical interference by the oil on or in the leaf tissue and recovery 
was apparently related to dissipation of the oil from the leaves. 
Transpiration was restored to original levels in the treated plants in 
3 to 5 weeks after treatment. Riehl and Wedding (58) studied the 



15 

relation of molecular structure of oil to effect on transpiration of 
lemon and lime plants. A 306-mol wt naphthenic oil and a 308-mol wt 
paraffinic oil both reduced transpiration more than 507o, but recovery 
was faster in plants sprayed with the naphthenic oil than in those re- 
ceiving the paraffinic oil. 

The effect of petroleum oils on photosynthesis and respiration of 
various plants has been studied. Knight et al . (36) reported inhi- 
bition of photosynthesis in citrus leaves by light (50 SSU) and heavy 
(106 SSU) oils, but recovery was faster in the plants treated with the 
light oil. The same workers observed a significant stimulation of 
respiration by the same oils. Other workers have reported increases in 
respiration of plants treated with oil sprays. According to Green and 
Johnson (30) respiration of bean leaves increased following application 
of low refined oils of less than 84 UR, but a reduction in respiration 
followed applications of oils of more than 84% unsulfonated residue. 
Green (31), working with oils of both high and low refinement on bean 
plants, apple leaves and twigs, and barley seedlings, found a general 
increase in respiration, but the effect of the low UR oils was more 
than triple that of the highly refined oils. McMillan and Riedhart 
(37) observed an increase in oxygen uptake by leaves of 'Valencia' 
sweet orange, Citrus sinensis , following application of pure hydro- 
carbons of a distillation range of 419 to 487 F, while those treated 
with pure hydrocarbons and spray oil of a distillation range of 552 F 
and higher showed a definite decrease in respiration. 

Schroeder (62) reported that inhibition of photosynthesis in apple 
foliage was directly related to viscosity and rate of application of 
the oil. Oberle et al . (41) obtained similar results with heavier 



16 

dormant- type oils. Riedhart (46) reported inhibition of photosynthesis 
of banana leaves by a 75-SSU paraffinic oil. 

Wedding et al . (98) reported a depression of both photosjnithesis 
and respiration in sweet orange and lemon plants sprayed with petroleum 
oil emulsions in amounts approximating the deposit level obtained in 
field applications in California. Recovery of photosynthesis occurred 
sooner in lemon plants than in orange plants. In no case did they get 
an increase in respiration as reported by Knight et al . (36), Green and 
Johnson (30), and Green (31). They attributed at least part of the re- 
duction in soluble solids of citrus fruits accompanying oil spray 
applications to inhibition of photosynthesis. 

Riehl and Wedding (57) compared naphthenic and paraffinic oils of 
different molecular weights as to their effect on photos3mthesis in 
citrus leaves. No consistent inhibition was observed with insecti- 
cidally efficient deposits of 150 (ig/cm^, but deposits of 300 to 600 
(j,g/cm greatly inhibited photosynthesis. The principal effect occurred 
in oil- soaked tissue. During the first week following application, 50 
to 60% reduction was detected. A tetrazolium test showed that cells in 
the oil-soaked tissue were not killed. They concluded that inhibition 
of photosynthesis was the result of interference with gaseous exchange 
caused by the presence of the oil, and that dissipation of the oil was 
accompanied by recovery of photosynthesis. Recovery by plants sprayed 
with naphthenic oils was faster than by plants treated with paraffinic 
oils. Results of a similar experiment by the same authors (59) showed 
that the difference in rate of recovery associated with difference in 
paraffinicity was greater for oils of comparable viscosity than for 
those of comparable molecular weight. 



17 

Injurious effects of oil sprays on citrus 

Various types of injury resulting from oil applications to citrus 
have been reported (2, 16, 19, 22, 34, 35, 45, 51, 52, 53, 61, 66, 67, 
83, 84, 89, 91, 92, 93, 99, 104, 105, 107, 110). Types of adverse 
effects reported were leaf and fruit drop, fruit burn, fruit blemishes, 
rough textured fruit, reduced soluble solids and acid, increased granu- 
lation, delayed degreening, crop reduction, upset of normal blossoming, 
increased water rot and decay of fruit in wet weather, dead wood, and 
increased susceptibility to freeze damage. According to Rohrbaugh (61), 
some writers have claimed various beneficial effects such as larger 
fruit, larger leaves, and better color, but most of these claims, he 
felt, were without foundation. 

Yothers and McBride (107) first reported a decrease in solids in 
fruit from oil- sprayed trees in Florida in 1929. Thompson and Sites 
(83), using oils of 72 and 100 SSU, concluded that oil sprays applied 
after 1 August either delayed or prevented the formation of maximum 
soluble solids, especially during the early part of the season. 
Thompson and Deszyck (91) observed a greater effect on fruit quality 
with 1.3% oil than with 0.7% oil in combination with parathion. 
Sinclair et al . (66) reported that applications of light-medium grade 
oils to citrus in California, at concentrations of 0.25 to 1.75%, caused 
reduction in the total soluble solids and that timing of application 
was relatively unimportant. However, Riehl et al . (54) found a defi- 
nite correlation between timing of oil sprays and fruit quality in 
California. Applications during the period November to June had the 
most adverse effect on solids. 



18 

Numerous workers (66, 68, 80, 82, 89, 100) reported retardation of 
the degreening rate of oil- sprayed citrus fruit. But the author found 
no report of studies having been made of the relation of oil properties 
to effect on fruit color, except that an 80-SSU oil retarded color 
development less than did a 95-SSU oil (100). 

A grade- lowering fruit blemish, referred to as "oil blotch," is 
associated with oil sprays applied in Florida when the fruit is between 
0.75 and 1,50 inches in diameter. Thompson (85) described the con- 
dition as being round in shape, varying from light to dark brown in 
color, and of a superficial nature; but it was a definite grade- lower- 
ing blemish. 

Thompson et al . (87) reported more than twice the amount of dead 
wood in oil-sprayed sweet orange trees than in either parathion- sprayed 
or unsprayed trees. Oil- sprayed tangerine trees dropped 10 times as 
many leaves following a February application as did those receiving 
parathion sprays. Thompson (92) found the greatest leaf drop to occur 
when oil applications were made just prior to, or during, the time of 
normal shedding of old or weak leaves and concluded that while oil 
sprays are the most common cause of leaf drop, tree condition apparent- 
ly is a factor where excessive drop occurs. Thompson (84) reported no 
difference in leaf drop or shock to the tree with oils of 72 to 100 SSU 
viscosity or oils of low and high refinement. However, Ebeling (24) 
reported heavy leaf drop following application of 2.0% heavy oil of 86 
UR, and decreasing drop with oils of 95 and 100 UR, respectively. He 
stated that leaf drop constitutes a rather accurate index of the phy- 
totoxicity of an oil. 



19 

Ziegler (110) noted 3 definite physiological responses of 
'Valencia' sweet orange trees in Florida following applications on 12 
May of an oil of 70 SSU viscosity and 83 UR at 1.66% concentration. 
These were: 1) size of immature fruit was retarded, except where the 
reduction of the crop was approximately proportional to reduction in 
leaf area; 2) the number of fruit borne in the succeeding crop was re- 
duced, and 3) the subsequent flush of growth was accelerated. He con- 
cluded that the insecticidal and phytocidal properties of mineral oils 
were closely correlated and applications of these must be timed to 
allow maximum deposit without detrimental plant reaction and minimum 
deposit for thorough pest control. 

California workers (76, 77, 78, 79) reported successful use of 
2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid as 
spray oil ammendments to counteract some of the adverse effect of oil. 
Addition of 4 or 8 ppm 2,4-D to the oil spray mixture increased yield, 
reduced both leaf and fruit drop, and had less effect on soluble solids 
in grapefruit than oil alone; the 2,4-D had no apparent adverse effect 
on trees other than some curling and distortion of young leaves. 

Specifications for Plant Spray Oils 
Five classes or grades of foliage spray oils are recommended for 
citrus in California (24). These are based on the work of Gray and 
DeOng (29), DeOng (18), DeOng et al . (19), and of Smith (72). Accord- 
ing to Ebeling (25), distillation range and per cent unsulfonated 
residue are the most valuable criteria by which summer oils can be 
standardized. The 5 recognized grades and identifying properties are 
given in Table 1. Ebeling (25) pointed out that these standards do 
not necessarily hold for oils applied to citrus in other states. He 



















20 




(U 


















1 3 


















.-( -a 


















3 -H 


















to to 


















C 0) 


















3 ^j 




















o 


(N 


CM 


CM 


^ 








e -a 


CTv 


C3N 


CJN 


CJ^ 


CJ^ 








3 (U 


















g 4-1 


















•H CO 


















C C 


















•r-l O 


















s -« 


















13 


















4J 0) Pn 


















C r-l 
















« 


4) r-l O 


CM 


-* 


CM 


1—1 


O 






to 


O -1-1 fO 


• 




• 


• 


• 






r-l 


•U vO 


vO 


m 


cn 


CJ^ 


00 






M-t 


>-l to 


vO 


in 


-* 


ro 


i-H 






o 


0) -f-l 4-1 
PM 13 CO 
















>% 


















to 


















u 


















a. 


















CO 


















to 


B^ 


u-1 


CO 


u-l 


00 


r^ 






•H 


H O 


r^ 


o 


r-H 


(N 


CM 






c 


O t3^ 


\o 


r^ 


I^ 


r^ 


r~. 






^ 


4-1 












• 




o 


• • 












4-1 




4-1 


" 4-1 












b 




•rl 


fn o 












CO 




1— ( 














o< 




cfl 


' c 
















(J 


4) O B~2 


i~^ 


00 


n 


vO 


i-( 


(3 






M -H O 


t-i 


og 


-* 


in 


1^ 


•H 




U 


3 +j in 


VO 


vO 


vD 


\D 


vO 






O 


J-> CO 












•• 




4-1 


CO r-l 

u >-i 












00 

m 




to 


<U •r^ 
















C 


a -U 












• 




o 


g CD 












a 




•I-l 


(U -1-1 s~s 


u-i 


r-H 


CM 


u-i 


CM 






4J 


H -a in 


u-i 


I^ 


00 


00 


1—1 


•» 




CO 




U1 


m 


in 


in 


^ 


^^ 




o 














in 




•1-1 














<N 




4-1 














N^ 




•H 


















o 














60 




(U 














C 




CU 






a 




g 




•i4 




w 






3 

•H 




•H 




1-1 
(U 
XI 




• 


(U 




(U 




SJ 




w 




1-1 


cO 




S 

1 


S 


S 




M 




0) 


U 


4J 


4-1 


3 


>. 


^ 


4) 




1—1 


o 


x; 


•C 


•1-1 


& 


§ 


4-t 




J3 




60 


60 


T3 


CO 


^ 




CO 




•1-1 


•H 


«i 


(U 


<U 




H 




hJ 


hJ 


s 


K 


K 


CO 





• 21 

stated, "It is known, for example, that oils as low as 80 UR, which 
would be excessively injurious to citrus trees in California, can be 
safely used in Texas, Florida, and Mexico. It appears that in more 
humid regions a citrus tree is not so adversely affected by oil as in 
California, and that oils of a lower degree of refinement can be safely 
used." 

Chapman and Pearce (7) first published standardized specifications 
for dormant spray oils for New York in 1947. They recognized 2 types, 
"regular" and "superior"; both were 100-SSU oils but of different re- 
finement. In 1959, Chapman (8) presented specifications for a "70- 
second superior oil" in addition to the 1947 "100-second superior oil." 
Chapman et al. (9) added to these a "60- second superior oil," dropping 
the 100-second oil from the recommendations. Specifications for these 
are presented in Table 2. Some oils currently used in Florida on cit- 
rus are patterned after Chapman's "70-second superior oil." 

Dean and Bailey (14) published tentative specifications for oils 
for use on Texas grapefruit in 1961. They specified unsulfonated 
residue, 92% minimum; distillation (760 mm Hg) , 50% at 716 F with a 10 
to 90% range of 85 F; and a neutralization number of 0.03 minimum. 

No grade standards have been established for oils used on citrus 
in Florida. The oils currently in use vary as follows: viscosity, 60 
to 110 SSU; 50% distillation point, 651 to 788 F; 10 to 90% distil- 
lation range, 52 to 261 F; average molecular weight, 300 to 350; and 
refinement, 80 to 96 UR (compiled from specification data for various 
commercial oils) . 



u 
o 

» 

<u 

13 



0) 

u 



CO 
to 



3 
M 

o 

4-1 

T) 
(U 
•H 
i-l 
P. 



o 



CO 

e 
o 



to 
u 



u 

0) 

a. 
en 



r-l 

E-1 



C 

o 

u 

0) 
CO 

o 



13 

c 
o 
u 
cu 

CO 

I 

o 
1^ 



•H 
O 

o 

•H 
M 
0) 
CX 

to 



•1-1 
o 

i-i 
o 
•1-1 
I-l 

(U 

a 

3 
to 



CM 

vO 

I 















13 
C 
O 
U 
0) 
to 

o 
o 



o 

CM 

I-l 
I 

o 

^7^ 



cd 
to 
u 

> 

•H 



o 



^ 















00 




'*:■•'■' 




22 


<N 


o 












in 








ON 


tN 










+ 1 

m 
<}• 

O 

1-1 


r~- 




• 

I— 1 




CNJ 


O 












O 




CO 




C3N 


CM 




c 
I— 1 


O 

c 
o 

•H 
■U 
M 
O 




+ 1 

o 


C3> 




4-1 

c 
& 

CO 

o 

t» 

c 




o 


O 




<u 












to 




a\ 


CO 




> 

•rH 
4J 
Cd 

1-1 

to 

n 
« 


0) 
4J 

to 
I-l 

1— 1 

•H 
4-> 

to 

•1-1 


(U 

o 

M 

4J 

tu 
a 








e 
a 
to 
x: 
u 

tu 
u 

tu 

c^ 




s 






M 












a 




•o 






a> 








<u 




CO 




•rl 






&• 








60 




JZ 




« 






§ 








g 




u 




u 






«j 






c 


!-i 


s 


§ 




T3 S-S 






c 


bO 




•1-1 


S-5 


3 


M 




tu 


•\ 




o 


53 




o 


O 


S 


■4-4 




i-l •> 


4J 




•H 






a 


0^ 


•H 






tfl •-N 


c 


('-^V 


•W 


c 






1 


^ 


'O 




c s 


•H 


g 


CO 


1 




s^ 


S~2 


S 




O 3 





3 


1—1 






o 


O 


s 


-^ 




M-l g 


a 


e 


rH 


O 




u-i 


1-1 


N— ' 


•i-l 




1-1 T-l 




•H 


•H 


vO 










a 




3 C 


M 


S 


4J 


!->• 














CO -i-l 


3 


to 












Q 




C B 


O 


s 


•H 
O 


4J 

to 










^ 





MATERIALS AND METHODS 

Oil Specifications ^. 

The oils used in these studies were obtained from the following 
major oil companies: Humble Oil and Refining Company; Gulf Oil Corpora- 
tion; Sun Oil Company; Shell Oil Company; Texaco, Incorporated; and the 
American Oil Company. Of these, Humble was by far the largest con- 
tributor, providing 23 narrow-distilling, experimental fractions and 10 
commercial oils. The other companies contributed both experimental and 
commercial products. Specifications on important properties of these 

oils appear in Table 3. The 3 narrow-boiling series provided by 

2 
Humble were comprised of paraffinic, naphthenic, and "reformed" frac- 
tions. These oils provided wide ranges of molecular weight, viscosity, 
and distillation temperature in which to study insecticidal, ovicidal, 
and phytocidal properties. The commercial- type oils included most of 
the oils presently used on Florida citrus plus several experimental 
materials. Specification data were provided by the oil companies; the 
methods hy which the data were obtained are indicated by footnotes to 
Table 3. 



■•■"Boiling" is used synonomously with "distilling" throughout this 
paper and refers to the 10 to 90% distillation range, unless otherwise 
specified. "Narrow- boiling" is a relative term applying to the first 
23 oils listed in Table 3; the remaining oils are commercial products 
of wider distillation ranges. 

2 
The word "reformed" in this paper refers to spray oils which have 

received special treatment to alter the component hydrocarbons; the 

reformed oils are predominantly paraffinic. 



23 













24 




fl 

























s.»i^ 












o w 












0^ ^ •> 


CN fO fO r^ vD 


vD •* r~ CM ^ 
CO «J m «* 1-1 


CM <t CO O CO 


r^ CO r^ r-«. OO 




1 1-1 0) 


^ F-i 1-1 CNJ ro 


fH 1-1 CO CM CO 


rH ^ CM 1-1 CM 




O -H 60 












CO Q 












•H H 


r .- 










-o 


;; V 












S~2 


1-1 CM CM 1-1 <)■ 


ON vo <t •* »* 


1-1 O vO 1-1 •* 


CM O vO 00 CO 




tM 


o 


cT\ CM m o n 


r~ m -* 1-1 CM 


vO 00 O CM 00 


o CM m r~ O 




-c •• 


(y\ 


in vo vc r-» r^ 


r» OO ON vO vO 


vo vo r^ p^ r^ 


vO vO vO vO r>. 




py O iM 














•H O 




... 


* >■ • 






(0 


•>iJ 












(U 


4) CO ,^-s 












•rt 


MrH 60 












T) 


3^ P3 


s^ 


1-1 ^ vo vo m 


CM i-( 1-1 1-^ m 


vo m o VO VO 


CO i-i m m ON 


3 


•U'H 


o 


00 1-1 >* e3\ 1-1 


m CO 1-1 cTv i-( 


m r» O 1-1 VO 


C?> 1-1 CO vO 00 


4-1 


CO 4-> E 


m 


in vO vO \D P^ 


r~~ 00 (Ti in vo 


vO vo r-. r^ r^ 


in vO vO vO vO 


U 


U •H 












(U 


a-o o 












u 


S vO 












a> 


4) M t^ 












si 


H ^-' 


^5 


0^ 0> 0^ •^ 00 


CO CM r^ CM oo 


ON VO CO 1-1 1-1 


m p~ o> r-( m 


u 


IM 


o 


r- O fO 1^ 0> 


«^ 1-* oo r^ o 


s^ vo r»- O m 


00 O CM vO r^ 






^ 


m vO vO vO vO 


f^ 00 00 m vo 


vo vo vo r^ t~. 


m vO vO vO vO 


C 














•H 


0) 










•o 


>. 










a> 


u 










to 

3 


H .H 


CT^ 00 0^ PO O 


CM vO CO «* vO 


O r-H ^ ON vO 


00 vo 1-1 r^ CO 


o o^ r>« \o m 


CM 1-1 O >* UO 


vo vD NO m CO 


CM CM CO 1-1 t-l 


(0 


u 


^ ro c^ CO c^ 


*^ CO CO CO CO 


c^ CO CO CO CO 


CO CO CO CO CO 


i-< 


00 










•H 

























a 


-^c 


q 


o o o in o 


in o m in o 


o o o o o 


m m m o o 












<u 


o 


s-s 


^ i-< CM r^ n 


1-4 m cjN oo m 


m 00 (3N o vo 


m r~ CM o ^ 


1-1 


•H 




p~ r~ r>. r^ t^ 


[•». vD vo m m 


vO vO vO r^ vD 


.^^ ^ m m m 


o 


u 












u 


f4 












4J 


m 












<u 















p- 


a, 




CJ^ O CM o -* 


.<t ON 1-1 CM o 


VO t^ r^ vo CO 


cjN vt in o o 












(4-1 


Q 


B~2 


en cTi m 00 CM 


in ON vo cjN 1— 1 


sj- 1-1 00 p- 1-1 


CM i-H r- cjN 00 


o 


u 




CM CM CM 1-1 CM 


CvJ CM Cvj CO •<}• 


CO CO CM CM CO 


in m •* -^ »* 


(0 


1-1 












OJ 


CO 












•H 


t) 












4J 


•M 












U 

p. 


42 


< 


1-H o 00 in vo 


1-1 1-1 vt CO O 


>* CO CO >* r^ 


vO o o o o 


CM O CM .<)• vi- 


CO in <f- CM <f 


O O CM CM CM 


1— 1 1-1 O 1— 1 1— 1 


o 


O 












u 












a 












CO 

3 
O 




vo 00 00 00 ^ 


vO o o <j- >* 


O vt o o o 


«^ CM vO vO CM 


in in in 1-t ro 


^ .* CO vo 1-1 


»* <f 1-1 «* m 


vO vO vO vO 1 — 


•1-1 




On On On 0> On 


ON ON On 00 C?N 


ON OS ON ON ON 


ON On On on On 


13 












> 


4-1 










u 


•1-1 4JU 










o 

H-l 


M CO |1« 

o 

O !=) O 


O O O 00 o 


O 1-1 O 00 vO 


00 cjN CO m CM 


vO -* r-» CO r-- 


1-t in o C3N i-< 


ON ON vO CM vO 


CM m C3N vO o 


t^ f-H t^ 00 ON 


CO 


to M O 


>d- <h in in r^ 


On ON ON ^ s^ 


in m in \D o 


<f m m vo r-. 


C 


•1-1 CO t-t 




1-1 CO 


1—1 




o 


> 










•H 












4J 












CO 












u 


60 1-1 


CM in m m CM 


m CO o o m 


m m in o in 


O in m m o 


•H 


5: 2 tl 


in ^ 00 o CM 


vO CO CM m vO 


OO ON O CM vO 


in vo 00 o CM 


U^4 
•1-1 

u 

a. 


< a s 


CM CM CM 00 CO 


CO «* m CM CM 


CM CM CO CO CO 


CM CNJ CM CO CO 




J2 


o m m m o 


m m o o m 


m m m o m 


o m in m o 


w 




Qi 


m vo 00 o CM 


vO CO CM m vO 


00 CJN O CM VO 


in vo 00 o CM 






S 


CM CM CM CO CO 


CO <* m CM CM 


CM CM CO CO CO 


CM CM CNl CO CO 


m 


1—4 


Z 


1 1 1 1 1 

PM Ph pH PU PM 


1 1 1 1 1 

PM PM PM pci p:; 


Pi Pi Pi eii Pi 


1 1 1 1 1 

Z Z Z Z iZ 


•H 












0) 


o 












1-1 




CO 










•§ 




• 


CM CO »* ^O r~. 


00 c^ o ^ CM 


CO -^ m vo r>. 


CJN O 1-1 CO .^ 




o 




1—1 1—1 rH 


1— 1 F-H I— 1 l-< 1— 1 


1-1 CM CM CnI CM 


H 




!S 























25 




e 














o 














•H Pn 














S~S -U o 














O fl) 














0^ i-l " 


vo ro in vo m 


00 o o ON m 


t^ ^^ in ON 1—1 


1-1 O O CM 






1 r-l 0) 


,-1 i-i .-1 r^ 00 


<7N .-1 O O CM 


CO <3N in r^ NO 


1 r^ 00 00 CM 






O -rl 60 




1-1 1-1 r-4 ,-4 


1-4 CM 


T-4 






(0 cS 














•H l-l 














•o 






' 










B^ 


o r^ vo CO t-H 


ON CM CN CM NO 


St cni p^ 00 m 


NO CO o -* 






14-1 


O 


in t^ 1-4 vo vo 


r^ CO CO CO CM 


r^ ON o t-i «* 


1 CM 1-1 m CM 






- C •• 


(^ 


r^ p^ cjo r^ r^ 


r^ r^ r^ r^ 00 


p^ p^ r^ r»~ On 


r^ oo r» p>> 






fH O M-l 
















•H O 
















•> 4J 
















0) rt /-v 












' 




M •-* 00 
















3 ^ PS 


S~2 


00 r». 00 t-i o 


CM 00 i-l O .-1 


oo p^ T-i NO oo 


St CO i^ NO 






•U -H 


O 


PO vO O CM CM 


CO r-» 00 oo m 


OO CO 00 NO oo 


1 oo NO 1-1 ^ 






cd 4J E 


in 


r^ P-. oo r^ r^ 


p^ ^ NO vo r^ 


NO r^ NO NO p^ 


NO r-~ r^ vo 






l-l U3 1 
















QJ •M 
















a.'O o 
















a vo 
















<U M r^ 
















HO"-' 


B-2 


«* s;J- i-H r~ vD 


1-1 CM CM CO 1-1 


r«. CO CM C3N ^ 


NO CO O CM 






<+A 


O 


CO vO O 00 r^ 


00 CM CO CM O 


CO ON in CO 00 


1 m CO 1^ O 








^ 


r-^. r-~ 00 ^ vo 


NO NO NO NO r^ 


nO nO no nO nO 


NO r-» NO NO 






<u 














4-1 
















oo --I 0^ CM ^ 


O St ON m •* 


NO m CO o CM 


O CJN CO o o 




<J^ 00 m O 1-4 


in m m o CO 


ON P^ NO O On 


O CO CO 1-4 ON 




a, 


CM CM CM ro CO 


CO CM CM CO CO 


CM CM CO CO CM 


CO CO CO CO CM 






TS 


Fti 


m in o o o 


o o o o o 


o o m 


CM O O O O 






c 


U 




• • • • • 


... 1 1 








O 


^s 


CJ^ O 00 CM O 


O CJN o r^ O 


O 00 CM 


00 CM CM St O 






•H 
4J 
•H 




^d" m •* vo vo 


r~ CO ■>* >i- r^ 


NO m p~ 


m r>- r^ NO m 




















09 

































g. 


!a 


o 00 in o o 


O O St O NO 


■* CJN C3N 


00 o o o o 








o 


• • • • * 


• • • ■ • 





• • • • • 






Q 


6^ 


O r^ r-4 m o 


r^ t^ p~. 1-4 t^ 


NO NO CO 


NO St St •* NO 






u 




m >* in CN) CO 


CM >* St m CN 


CM CM CM 


CO CM CM CM -^ 






.-1 
















n) 














- 


u 

•H 
















§ 




in p^ in o o 


O o NO o St 


NO 1-4 NO 


o o o o o 










• • • 1 1 








^ 


^s 


O — 1 O CO o 


CO St CM CM CM 


CO m CO 


in St St cni «^ 






O 




1-4 1—1 


r-4 1—1 


1-4 t-H 


r-t 






g-" 


CM 00 00 o o 


NO ^ O CM O 


O O 1-1 o o 


o o o o in 




m CO 1— 1 -vf- r^ 


m CJN «* in «* 


m m NO r~ 00 


CM CO m 00 CO 






0^ 0^ ON r^ 00 


ON P^ 00 On On 


00 00 cjN 00 r^ 


<7N ON ON 00 ON 






>; 














4-1 














•1-4 4JO 














CO CO pt, 
O 

O D o 


vD O O 4"- vO 


CO m ON CM m 


r^ 1-1 NO in o 


O O O NO ON 






.-( CM CM <J- ON 


St St CO St CM 


1-1 CM r~ O O 


CM in in NO NO 






CO w o 


CO O O 00 r^ 


p^ 00 00 p^ ON 


r^ 1-1 m 1^ O 


r^ p^ O 1^ r~ 






•r-l OT rH 
> 


.-1 CM <f 




1-1 t-4 


1-1 




TS 


60 .-1 


m m O p- r-~ 


o St St m 00 


r^ O O 


CM O r-. o O 




0) 


5; 2 t! 


vO ON "d- i-l >-l 


CO ON ON O ^ 


ON CO O 1 1 


St CM St 1-1 00 




•H 


< s > 


CO CO *^ CO CO 


CO CM CM CO CO 


CM CO CO 


CO CO CO CO CM 
















U 














a 




^ 


m m o 










o 




a 


vo o^ "^ St r~ 


NO o >* m 1-4 


CM CO O 






1 




1 


CO CO "^ p^ 00 
1 1 1 1 1 


ON 00 00 On I 
1 1 1 1 Plj 


1 1 NO .-1 CM 
PJ Pd 1 1 1 


CO 1-1 CM CO ^J 
1 1 1 1 1 




1 

CO 


1— 1 
•f-( 


2 


Z Z Z Ph P4 


Ph Z Z Z m 


pa PQ Pi H H 


H o o o a 
















<u 


o 














1-* 




CO 












•9 




• 


m r^ 00 On o 


rH CM CO »* m 


NO P^ 00 CJN O 


r-l CM CO ■* to 




n) 







CM CM CM CM CO 


CO CO CO CO CO 


CO CO CO CO St 


«*<*>* St «* 




H 




s 













o « 

CO 

•f^ u 



o 

0^ 





^ 1 


M 


C 


• . 


h 





<4-l 




•rl 


o 


•1 


4J 




V 


!fl 


/-s 


u 


i-H 


00 


3 


1-1 


K 


4J 


•H 




n 


^ 


g 


u 


M 


5 


4) 


•H 




at3 


O 


a 




vO 


(U 


M 


r^ 


H 


O 


s-' 



o 



M 






•O 



c 


u 


o 


fs; 


•rl 




4-1 




1-1 




(0 




o 




a 


^ 




o 


o 


s^ 


u 




i-( 




to 




u 




1-1 




e 


< 


V 


o 


£ 


B-s; 


o 





I-l 


WU 


m 


to p^ 


o 




u 


& o 


U) 


w o 


H 


en --1 



0) 

3 

a 

•rl 
U 

c 
o 
o 

I 
I 






60 rH 

> O ■•-> 

< s u 



•H 

o 



fo 00 CM r«» 
r-i CT\ m m 



vo tH vo n 
m r-i ON es 
r*. r~ vo rv 



o^ «M O vO 

r^ vO rH o I 



O O CM OO 
ITi ON 0> 00 I 
1^ vO vO vO 



B^ 


o rH 00 m 


1^ r-l o o 


O 


O t^ 00 CTn I 


rH U-l .* fO 


m 


r~ vo vO ^ 


r^ vo vo vo 



o 

z 



fo fo <^ vo 

s* r^ <^ vD 

vO vC vO vO 



in IT) ctn vo o 



oo r~- fo CM o 
CM CO fO ro d 



r-l 00 CM CM 

r-» CM 00 oo 
vo ^ m m 



rM r~ 
I I • • I 

CO on 



o 



CM 



.* 

^ 



o o 
• I '11 

«* CM 



O CM O 

• • • 

•^ VO >* 



o o o o o 
CO 1-1 in -sf cj> 

0^ ON 0> ON 00 



o CO NO m 00 

• • • • Ov 

CO r-i On n£) I 

O vO vO 00 in 

r-t 00 



-* o 

00 I r-l I 

CO CO 



m 1-1 CM CO rH 

I I I I I 

O CO CO CO ■< 



vO r^ 00 ON O 

•d- <r >d- sr m 



o o 






o o 

"^ CM 
CM <N 



O O 
CM (N 



00 vO 
+ + • • 
00 tM <)■ CO 
00 On ON On 



m o 00 vo o 



vO vO 00 r^ O 
r~- in in m vo 



o CM m in 

r-l 1-1 r^ r^ 

fO CO CM CM 



r-l CM r-l CM O 

I I I I VO 

a o hJ t-J I 

Z Z en CO fXi 



r-l CM CO >i- m 
m in in in in 





1 

u 

(U 
M-l 
0) 
M 

g 
•rl 

c 

0) 

> 


• 

CO 

x: 

4J 

i 
IS 

1-4 
•H 






26 

• 




M 


s 






(0 






^4^ 


•rl 
CO 






1 




CO 


U 






«j 




V4 

(U 


O 






1 




.a 


•* 










C 


vO 
< * 






rH 




0) 


,^ 


• 
CO 




9 




o 
u 


g 


g 




to 




0) 

13 


4-1 


.a 

Id 




O 




CO 


•rl 


o 




vO 




I-l 


> 


•rl 




i-( 


• 


0) 




e 




r-l 


CO 


4J 


0) 


•rl 




(J) 


C 


4J 


u 


<4-l 




o 

•H 


rH 


§ 


13 




g 
^ 


4-> 

to 


u 


)-l 


13 




u 


(U 


o 


a 




•rl 


j; 


tj 








<4-l 


4-1 


o 


II 




U-l 


•M 


o 


to 






O 


o 






PL4 






0) 


r-l 


c 


o 




N 


a. 


r-l 


•rl 








to 


CO 




• M 




0) 






«\ 


CO 




4J 


M-l 


■ f\ 


r-l 


C 




o 


o 


u 


to 


O 




» 




•rl 


to 


■a 






(U 

r-l 




(U 


13 




5 


CO 


4J 


> 

•rl 


u 




•g 


*J 


42 


C 


CJ 








a 


P 


•rl 




4» 


u 


to 




C 






<u 


a 


4J 


(U 




u 


60 




r-l 


J3 


• 


U 


II 


O 


4-1 


to 


T) 


to 




J3 


J2 


•o 


^ 


1—1 


z 


>^ 


O. 


o 


O 






to 


CO 


£ 


U 


CO 


. •» 


cn 


c 


4-1 


^ 




t3 






CD 


e 


5i 


o 


II 


B 




o 


e 


4-1 






Pi 


^1 


h 




z 


u 


•r4 


m 


o 


CJ 


o 






IM 


•rl 




r-l 


00 


c 


<u 


4-1 


• w\ 


1-1 


PC 


3 


u 


to 


CO 


B 




u 


II 


B 


c 
o 


•3 

CO 


1 


•a 




c 


^ 








Pd 


•rl 


13 


M 


o 


<u 




i4 


O 


r-l 


u 


• A 




u 






(U 


O 


@ 




r. 


S 


> 


•rl 


o 


o 


r^ 


o 




c 


u 


•rl 


00 


M 


CO 


•rl 


M-l 


4-1 


CM 


C4-I 


U 


<4-4 




to 


1 




cu 


<4-l 


■o 


Q 


a 


"O 


^ 


to 


<U 


o 




lU 


1 


\i 


4-1 
I-l 


13 


g 


4J 

u 


c 


a. 


<U 

> 


II 


^ 


> 


r-l 


II 


c 






d 


•H 




o 


<! 


>N 


o 


«° 


Pm 


(J 


o 


CQ 


o 


CO 


ja 


o 


•a 


<U 


<4-l 



27 

Preparation of Oils 

Measurement of oil deposits on sprayed fruit and plant surfaces 
required the addition of an indicator dye to the base oils. An oil- 
soluble, water- insoluble red dye, DuPont Oil Red A (17), was added to 
each oil at approximately 2.5 g/liter. Mixtures of oil and dye were 
heated in a water bath to about 140 F and then were shaken continuously 
for several hours to obtain maximum dye concentration in the oil. 
Finally, the solutions were drawn through a medium- porosity fritted- 
glass filter to remove any undissolved dye particles. These stock 
solutions of dyed oils were used in all toxicity and phytotoxicity 
studies. 

The oils were formulated as emulsifiable oils in the laboratory as 
needed. An oil-soluble, non-ionic emulsifier, Experimental emulsifier 
9D-207 (Rohm and Haas Co., Philadelphia, Pa.), consisting of alkyl aryl 
polyether alcohol plus a non-ionic solubilizer, was used. Extensive 
tests under the conditions of this work showed that 0.4% (v/v) 9D-207 
gave adequate and similar emulsification for all the oils tested except 
the 2 heaviest fractions of the narrow-boiling paraffinic and naphthenic 
series. P-435 and P-520 required 0.6% and 0.8% respectively, and N-395 
and N-440 required 0.5% and 0.6%, respectively. The emulsifier was 
measured volumetrically with a calibrated dropping-pipette and added to 
each oil. The 2 materials were thoroughly and uniformly mixed by 
stirring vigorously for 3 to 5 min, depending on the volume of oil. 

Application of Oils in Laboratory Studies 
The oils were applied as dilute aqueous sprays with a laboratory 
air-blast sprayer (65) similar in performance to the commercial air- 
blast sprayers widely used by Florida citrus growers. The idea behind 



28 

this method of application was to duplicate the type of deposits ob- 
tained in field spraying. The spray unit, shown in Figure 1, consisted 
of the following main components: 

A. Blower, high velocity centrifugal; manufactured by Ideal 
Industries, Inc., Sycamore, 111,; 1.33-hp universal motor, 
11,350 rpm; "egg-crate" air straightener vanes attached 

at outlet; discharge velocity 6,000 fpm. 

B. Electric motor for pump; 0.75-hp; 1,725 rpm. 

C. Pump, manufactured by Hypro Engineering, Inc . , Minneapolis, 
Minn., Model 6500; nylon roller impeller, positive displace- 
ment; operated at 500 rpm. 

D. Spray tank, stainless steel; tapered botton, center drain; 
4,000-ml capacity. 

E. Pressure regulator and gauge with by-pass to the tank. 

F. Sprayer nozzle of "whirl jet" type as used on "Speed 
Sprayer," but with 3/64- inch orifice; stainless steel; 
centered 3.25 inches in front of blower outlet; mounted 
on 1/8- inch pipe to minimize volume of stagnant liquid 
in the line beyond the shut-off valve. 

G. Deflector vanes for shaping the air blast to a vertical 
column of uniform velocity and spray impingement above 
the turntable. 

H. Operating lever with air baffle that extends over blower 
outlet. Lever is linked to the quick shut-off valve to 
start and stop air and liquid simultaneously. 

I. Turntable centered 7 feet 9 inches from the sprayer nozzle; 
operated at 15 rpm. 

Emulsification of the oils was obtained by circulating the desired 
amounts of emulsifiable oil and water through the spray unit 4 times, 
or 32 sec for each 1,000 ml emulsion. The shearing action of the pump 
and pressure regulator and the high velocity stream of liquid returning 
to the tank produced a uniform emulsion. 

The liquid was atomized through the nozzle at 70 psi and dis- 
charged into a 6,000 fpm-air blast. At the start of each spraying in- 
terval, the quick shut-off valve was opened for about 3 sec to clear 



29 




Figure 1. Laboratory air-blast sprayer. A, high velocity blower; B, 
motor; C, pump; D, spray tank; E, pressure regulator; F, nozzle; G, 
deflector vanes; H, operating lever: I, turntable. 



,,v 



30 

the line of stagnant liquid. A stop watch was used for timing the 
spraying interval. As the timer-hand approached the starting time, the 
blower was turned on to build up speed. When the timer-hand reached 
the starting point, the operating lever was raised, thereby opening the 
valve and injecting the spray into the air blast released simultaneous- 
ly by a baffle plate on the end of the lever. At the end of the spray- 
ing interval, both liquid and air were stopped instantly by reverse 
action of the lever. 

Uniform coverage was obtained and the spray was applied just to 
the point of runoff by spraying fruit for 3 revolutions, or 12.3 sec, 
and potted plants for 4 revolutions, or 16.4 sec. Plants were sprayed 
individually by placing the container directly in the center of the 
turntable. Individual fruit were placed stem-end up on a tripod at the 
center of the turntable, in which position the sides of the fruit re- 
ceived a uniform coverage of spray droplets (Figure 2). No attempt was 
made to spray the ends of the fruit because both mortality counts and 
oil deposit determinations were made only on the equatorial area of the 
fruit. Generally, 8 fruit were sprayed from each 4,000-ml tank of 
spray. Five infested fruit served as replicates for each treatment, 
and 3 fruit, occupying positions 1, 4, and 7 in the spraying sequence, 
were used for deposit determinations. Two shallow grooves were cut 
around each deposit fruit before spraying to define the equatorial area 
on which the deposit was to be measured. 

Oil deposits obtained on fruit surfaces with the laboratory 
sprayer were in direct linear relationship to the oil concentration in 
the spray. The coefficient for regression of deposit (p-g/cm^) on con- 
centration (as per cent oil in the spray) was 0.6732 x 100 with a 95% 



31 




Figure 2. Spray coverage obtained on fruit with the laboratory air- 
blast sprayer. A, fruit sprayed with oil at 1.0% concentration 
containing fluorescent dye to show the distribution of the oil; B, 
unsprayed fruit. Photographed under ultra-violet light. The 
rectangular area on fruit "A" was left unsprayed to show the con- 
trast between sprayed and unsprayed surface. 



32 

confidence interval for slope of 0.6237 to 0.7227. This was computed 
from data for 8 oils of 3 types applied on 4 different days. Regres- 
sions for the individual oils were very close to the 8-oil average, 
with slopes within the range 0.64 to 0.72. One per cent oil emulsion 
usually deposited 66 to 76 |ig/cm on the equatorial area of fruit. 
Similar deposit levels were obtained on plants. 

Oil Deposit Determination 

Oil deposits obtained on sprayed fruit and leaf surfaces were 
measured spectrophotometrically by the method of Riehl et al . (50), 
with modifications. The dyed oil was removed from the sprayed surface 
by solvent- stripping with dioxane (1,4-diethylene dioxide). The dye 
content of the strip solution was determined and used to calculate the 
total amount of oil recovered. 

A Beckman Model DB spectrophotometer, with a 40-mm rectangular cell, 
was used. Readings were taken at 524 mfi, the wavelength of maximum 
absorbance for Oil Red A in dioxane. A series of standards of known 
concentrations of the dye in dioxane was prepared and used to determine 
the regression of dye concentration on per cent absorbance. The re- 
gression coefficient (0.3093) was subsequently used to calculate the 
dye content of solutions of unknown dye concentration. 

The dye content of each oil was determined by weighing triplicate 
samples (about 15 to 20 mg) to the nearest 0.1 mg on an analytical 
balance, diluting each sample with dioxane to 25 or 50 ml (depending on 
the weight and relative dye concentration of the sample), and reading 
the per cent absorbance in the spectrophotometer. The per cent dye in 
each oil sample was calculated by the following equation: 



33 



per cent dye = Total pg dye ^ ^qq ^ (A)(b)(vol) ^ ^qq 
Total \ig oil Total (ig oil 

where A = spectrophotometer reading in per cent absorbance x 10 
b = regression coefficient, 0.3093 
vol = volume in ml to which weighed oil sample was diluted 
Total |ig oil = mg oil x 1,000. 

The oil deposit on fruit was measured only on an equatorial band 
of 1.0 to 1.5 inches on immature oranges and 2.0 to 2.5 inches on im- 
mature grapefruit. This area was defined by the shallow grooves near 
and around each end of the fruit, as described earlier. The sprayed 
fruit was held with its polar axis horizontal over a 6- inch glass fun- 
nel for stripping. The fruit was slowly rotated on axis and a jet of 
dioxane from a 250-ml polyethylene squeeze-bottle was directed at the 
equatorial area. The flow of solvent followed the curvature of the 
fruit and did not run into the grooves along the margins. The strip 
solution was collected in a graduated cylinder for measurement. From 
10 to 15 ml of solvent were sufficient for removal of the oil deposit 
from immature Valencia oranges and 20 to 30 ml were adequate for near- 
ly-mature grapefruit. The oil deposit was measured on 3 fruit for each 
tank of spray or treatment. The rind was removed from the equatorial 
bank of each fruit and traced on paper; the area was measured with a 
planimeter. The oil deposit was calculated as follows: 

txg oil/cm^ = (A)(b)(vol) 
(cm2)(D) 

where A = spectrophotometer reading of the strip solution in 
per cent absorbance x 10 
b = regression coefficient, 0.3093 
vol = volume in ml of strip solution 

2 2 

cm = surface area in cm from which the deposit was 

stripped 

D = per cent dye in the oil. 



34 

Oil deposits on leaves of sprayed potted plants were determined in 
the same manner as described above for fruit. Either 2 leaves selected 
at random from each of 5 treated plants or 10 leaves from a single 
plant constituted a deposit sample. Each leaf was carefully removed 
from the plant with forceps and scissors, and held over the funnel for 
stripping. Approximately 5 ml of solvent were sufficient for washing 
the oil from both sides of the leaf. The leaves were traced on paper 
and measured with a planimeter. The area was doubled to account for 
both leaf surfaces. 

Insecticidal and Ovicidal Efficiency Studies 
Florida red scale studies 

The insecticidal efficiency of the oils was studied using adult 
female Florida red scale as the test insect. A natural infestation of 
this species on English ivy, Hedera sp., was the source of test materi- 
al. Crawlers from these scales were used to infest nearly-mature 
grapefruit in the laboratory. These scales were allowed to grow to the 
early third stage at which time treatments were applied to the infested 
grapefruit. 

Infestation . --Laboratory infestations were obtained as follows 
(Figure 3): ivy leaves heavily infested with crawler-producing red 
scale were picked, brought into the laboratory, and cut into small sec- 
tions, each section bearing several female scales. Five to eight of 
these leaf sections were stapled. between 2 strips of cheesecloth 
measuring 1.5 x 14 inches. Nearly-mature grapefruit were harvested, 
brought to the laboratory, washed, and then placed stem-end down on 
2.5-inch diameter juice cans filled with wet vermiculite, where they 
remained throughout the infestation period. The prepared strips were 



35 




Figure 3. Method of infesting grapefruit with Florida red scale for 
laboratory studies. A, ivy leaves with natural infestation of 
crawler-producing female scales; B, cheesecloth strip with infested 
leaf sections; C, strip of leaf sections wrapped firmly in position 
around the equator of a grapefruit to allow crawlers to transfer; D, 
typical infestation obtained by this method, at time of treatment 
application (4.5 weeks after infestation). 



36 

wrapped firmly around the equatorial bands of the grapefruit with the 
infested side of the leaf sections adjacent to the fruit surface. As 
the leaf sections began to dry out, the scale crawlers migrated to the 
surface of the grapefruit and settled in the equatorial area. The 
fruit were checked periodically and when 200 to 300 crawlers had 
transferred to the fruit, the strip of leaf sections was removed and 
placed on another fruit. This period of infestation varied from under 
24 hours up to 48 hours. The 48-hour limit was imposed to maintain a 
maximum 2-day spread in age of the insects, since age has been found to 
affect the response of scale insects to insecticidal treatments (22) . 
This level of infestation resulted in an average of about 100 third- 
stage females per fruit at the time of treatment. .,. 

As the fruit became infested, they were transferred to a 24 x 24 x 
2-inch wooden tray in an enclosed chamber for holding. The tray con- 
tained a 1.5-inch layer of wet vermiculite overlain with double- thick- 
ness cheesecloth (Figure 4) . 

Holding infested fruit . --It was necessary to hold large numbers of 
detached grapefruit for 51 days in the laboratory. Attempts to hold 
fruit in the absence of a water supply failed due to dehydration and 
shriveling of the rind. This was alleviated by holding the fruit stem- 
end down in moist vermiculite. By this method, dehydration was prevented 
and approximately 90% of the fruit remained turgid throughout the hold- 
ing period. Another serious problem was that of a stem-end rot of the 
fruit. This condition was alleviated by dipping the stem-end of each 
fruit in a 5% thiourea solution immediately after harvesting and weekly 
thereafter up to about 4 weeks. The number of fruit lost due to the 
rot was reduced to less than 10%. These fruit were discarded as 



37 







Figure 4. Scale- infested grapefruit on moist vermiculite in holding 
tray. 



38 

detected and were never included, in the treatments. Where the rot set 
in after treatment, its advancement was observed and if the affected 
area extended into the scale- infested equatorial area before the sched- 
uled time for mortality counts, the scales were counted early to avoid 
loss of a treatment replication. These early counts were within 4 to 7 
days of the scheduled mortality counts and the results did not differ 
markedly from the other replicates of the same treatment. 

The infested grapefruit were held in a chamber made of 2 x 4- inch 
wood framing, enclosed on the sides with translucent polyethylene 
sheeting, but open at the top and bottom for ventilation (Figure 5). 
The size of the chamber measured 8.5 x 2 x 7 feet in width, depth, and 
height, respectively. Six shelves, spaced 12 inches apart, vertically, 
starting 18 inches above floor- level, accommodated 24 trays. Each tray 
held a maximum of 36 medium-size grapefruit, with adequate clearance 
between fruit. Conditions inside the chamber were maintained at 78 + 
4 F and 70% + 5% relative humidity. Lighting, in alternating 12-hour 
light and dark periods, in phase with the diurnal cycle, was provided by 
six 48- inch, 40-watt "daylight^ fluorescent bulbs hanging vertically on a 
wall immediately behind the chamber, and overhead room lights of the 
same type in front of the chamber. Diffusion of the light by the 
translucent polyethylene sheeting resulted in fairly uniform distribu- 
tion of the light inside the chamber. 

Scale devel opment, treatment, and mortality counts .--Treatments 
were applied when the female scales reached the early third stage of 
development. Under the conditions of this work, the insects required 
approximately 4.5 weeks to reach this stage. Treatments were scheduled 
32 to 33 days from the date of infestation and mortality counts were 



39 




Figure 5. Holding facilities for infested fruit in laboratory studies, 
A, chamber for holding trays of scale- infested grapefruit; B, racks 
supporting immature oranges infested with citrus red mite eggs. 



40 

made 18 days after treatment. The scales killed by the oil were easily 
identified by the brown discoloration of the body in contrast to the 
bright lemon- yellow color of live, healthy scales. Mortality was de- 
termined by turning the scale armor and inspecting the condition of the 
insect's body under 3X magnification. Only the scales in an equatorial 
band of 2.0 to 2.5 inches were considered. 

Testing the oils . --The testing of the oils against Florida red 
scale included dosage-mortality tests for selected oils of the 3 nar- 
row-boiling series and screening of the commercial- type oils at 2 
levels of application. 

Dosage-mortality tests were run on 6 selected oils of the 
naphthenic and paraffinic series and 5 of the reformed series. Each 
oil was applied at 8 concentrations, each replicated on 3 scale- infested 
fruit. Therefore each point on the dosage-mortality curves represents 
the response of approximately 300 individuals. In these tests, all 
dosage levels for the oils in a given series were applied on the same 
day. 

The dosage-mortality data were submitted to the University of 
Florida Computing Center for analysis. Probit regression lines were 
fitted according to the methods of Finney (26), giving the maximum like- 
lihood solution with adjustment for natural mortality. The input data 
were oil deposit (|j.g/cm ), total scales, and the number killed for each 
deposit level. The computer print-out provided regression coefficients 
and both LD^q and LD95 values with their 95% confidence intervals. 

The commercial oils were compared at 0.5% and 1.25% oil concentra- 
tion in randomized block experiments with 5 replicates for each treat- 
ment. Due to the large number of oils tested and differences in age of 



41 

the insects from group to group, it was necessary to apply the treat- 
ments over a period of 5 days. The data were corrected for natural 
mortality by use of Abbott's (1) formula to equate for difference in 
time of application. Natural mortality among the check groups varied 
only from 2.3 to 6.5%. The results were expressed as corrected per 
cent kill since the number of scales varied from fruit to fruit. Since 
percentage data tend to be binomial in distribution (74), the corrected 
per cent kill data were transformed by the arcsin transformation in 
order that the assumptions of normality, additivity, and homogeneous 
variance in the analysis of variance could be met. Analysis of vari- 
ance was run on the data and the significant differences between means 
were determined by the Duncan Multiple Range Test (20). 
Citrus red mite studies 

The ovicidal properties of the oils were studied using eggs of 
citrus red mite. Infestations of eggs were obtained on immature 
'Valencia' oranges in the following manner. One day prior to use, 
the fruit were harvested an.d washed, and the ends of each were coated 
with paraffin to confine the oviposition activity of the mites to an 
equatorial band of 1.0 to 1.5 inches, and to provide mite- free areas 
for handling the fruit. Thirty to forty adult female mites were hand- 
transferred to each fruit from plants growing in a greenhouse. After a 
2-day oviposition period, the fruit were inspected under 15X magnifica- 
tion and approximately 100 eggs were marked for post- treatment identi- 
fication by encircling each with India ink. The infested fruit were 
held before and after treatment under controlled conditions of 78+4 F, 
65% + 10% relative humidity, and a 12-hour light period in phase with 
the diurnal cycle. Lighting consisted of a mixture of natural and 



42 

fluorescent light. The fruit were supported on racks made of 0.5-inch 
plywood and No. 8 finishing nails, as shown in Figure 5. Treatments 
were applied on the third day after infestation and mortality rates 
were determined 8 days later by counting the numbers hatched and not 
hatched. The controls were sprayed with water in the same manner as 
the treatment applications. 

Representative oils from the 3 series of narrow- boiling fractions, 
selected to cover the ranges of molecular weight, viscosity, and 50% 
distillation point, were tested. Dosage-mortality relationships were 
established by applying 7 to 10 concentrations of each oil. Each con- 
centration was applied to 5 egg-infested fruit in a randomized block 
design. Thus each point on the dosage-mortality curves represents the 
response of 400 to 500 eggs. Due to the problem of infesting a large 
number of fruit with enough mite eggs of known age, it was not possible 
to apply all concentrations of an oil on the same date. However, 
dosages sufficient to establish the effective ranges were applied in 
initial tests and subsequent tests were conducted under the same 
environmental conditions to add supplementary points to the dosage- 
mortality curves. The data were analyzed by probit analysis in the 
same manner as were the Florida red scale data. 

In Field Experiment No. 1, described below, residual control of 
spider mites by 4 oils was determined. Spider mite counts were made 1, 
4, and 7 weeks after spraying as follows: 25 leaves were picked from 
each of 4 trees in a plot; eggs and active stages of mites on the 100 
leaves were collected by brushing onto a rotating circular glass plate 
(6 inches in diameter) covered with moistened glue; counts were made of 
the eggs, immature stages, and adult females of both citrus red mite 



43 

and Texas citrus mite on one-fourth the surface of the plate. These 
counts were multiplied by 4 to obtain an estimate of the total numbers 
on the 100 leaves. This is the standard technique used by entomolo- 
gists at the Citrus Experiment Station in making spider mite counts in 
miticide experiments. 

Phytotoxicity Studies 
Laboratory experiments 

Studies were made to compare the effects of oils of different 
molecular weight and base-type on the rates of respiration and transpi- 
ration of potted 'Pineapple' sweet orange seedlings. Simultaneously, 
observations were made of any abnormal reactions by the plants to the 
various treatments, such as leaf drop, leaf burn, and oil- soaking. The 
plants used in these studies were grown from seed in the greenhouse. 
Seedlings were transplanted from seed flats to 46-ounce juice cans 4 to 
6 months after planting. The potting medium was a 3:1:1 mixture of 
soil, peat, and vermiculite. The plants were approximately 1 year old 
when used. 

Respiration studies . --The rates of oxygen uptake by leaves of 
'Pineapple' sweet orange seedlings, sprayed with light (305 mol wt) and 
heavy (365 mol wt) fractions of both paraffinic and naphthenic oils, 
were determined. The oils were applied at 1.5% concentration. 

The plants were held both before and after treatment under green- 
house conditions with temperature fluctuation in the range of 60 to 90 F. 
Six plants, selected for uniformity in size and appearance, were as- 
signed to each treatment. Five pairs of adjacent leaves were selected 
on each plant and 1 of each pair was protected from the spray by 
shielding with aluminum foil during the spraying operation. The 



44 

unsprayed leaf served as the check on the adjacent sprayed leaf. One 
pair of leaves per plant was harvested each sampling date, starting 
with the basal-most pair and working up the plant on successive sam- 
pling dates. Thirty 0.25- inch discs were taken from each leaf with an 
ordinary hand-grip paper punch. Hence, 12 samples of 30 punches each, 
6 sprayed and 6 unsprayed, were run for each oil. The 30 discs from a 
single leaf constituted a sample. 

Oxygen uptake was measured by standard manometric techniques using 
a 14-flask Warburg respirometer . The flasks were of 16-ml capacity 
with 2 side arms. The ambient CO2 level was maintained by placing 0.2 
ml 10% KOH in the center well of each flask to absorb the evolved CO2. 
The flasks were kept dry, but 1 ml distilled water was placed in 1 side 
arm of each flask to maintain constant relative humidity. The flasks 
were shaken at 100 cycle/min in a water bath maintained at 25 + 0.1 C. 
The operation was carried out in a 68 F darkroom. 

A manometer- calibration period of 50 min was followed by O2 uptake 
determinations for 2 successive 30-min and one 60-min periods. The 
total O2 uptake during the last 2 hours was used to calculate the res- 
piration rate in ^,1 02/cm^ per hour. Determinations were made 1, 3, 7, 
and 14 days after treatment. The rates of the treated leaves were con- 
verted to per cent of the rates of the untreated leaves and these 
values were used for comparing the different treatments on each sam- 
pling date. An analysis of variance was run on the data. 

In a follow-up experiment, the heavy paraffinic fraction, P-365, 
was applied at 2.0% concentration as a drenching spray to 6 plants. 
The same procedures were followed as in the above experiment except 
that the sample size was increased to 48 leaf punches. Respiration 



45 



rates were measured 1, 3, and 7 days after treatment. The total O2 
consumption per sample during the 2-hour period was used to compare the 
adjacent sprayed and unsprayed leaves. The differences between treated 
and non- treated leaves were tested by the "t" test. 

Transpiration study . — The effect of light (285 mol wt), medium 
(320 mol wt) , and heavy (365 mol wt) fractions of paraffinic and 
naphthenic oils on the transpiration rate of treated 'Pineapple' seed- 
lings was determined by methods somewhat similar to those of Riehl 
et al. (56). The plants were selected for uniformity in stem height 
and number of fully expanded leaves. All but fully expanded leaves 
were removed from each plant and additional new growth was removed as 
it appeared so that the leaf surface area remained constant. Soil 
moisture was equalized by bringing each container of soil to field ca- 
pacity and allowing 1 day for excess water to leach and drain off. The 
weights of the plants and containers were then determined and these 
weights were used as the initial weight thereafter. The containers 
were placed in polyethylene freezer bags and sealed against evaporation 
loss of soil moisture by gathering the top of the bag firmly around the 
base of the plant and taping with masking tape. Transpirational water 
loss was determined as the difference between successive weights of the 
plants at 24~hour intervals, weighing to the nearest 0.1 g. The soil 
moisture was replenished after each 50-g loss by transpiration. Pre- 
treatment determinations revealed a uniform transpiration rate varying 
directly with number of leaves per plant. A randomized block experi- 
ment was set up with 7 treatments replicated 5 times. Blocking was 
on the basis of leaves per plant and position on the laboratory table. 
The oils were applied at 1.5% concentration in the dilute spray and 



46 

check plants were sprayed with water in the same manner as the treat- 
ment application. The plants were held in the laboratory at 78 + 4 F 
and 60% + 10% relative humidity. Alternating 12 hours light and dark 
prevailed. Illumination was provided by four 48- inch 40-watt "day- 
light" fluorescent bulbs placed 30 inches directly above the tops of 
the plants. 

Weighing was continued to 70 days after treatment application. 
The difference between 2 successive 24-hour weighings was divided by 
the total leaf area (considering only 1 side of the leaf since essen- 
tially all the stomata of citrus leaves are on the abaxial surface) to 
obtain the rate in mg/cm^ per 24 hours. The data were analyzed in this 
form. 
Field experiments 

Two experiments were conducted to obtain phytotoxicity data under 
field conditions. Block No. 23 of the Citrus Experiment Station groves 
was used for these studies. The trees were 'Hamlin' sweet orange on 
rough lemon rootstock, 6 years of age, and 8 to 10 feet in height. 
Five treatments, consisting of 4 oils and a check, were applied in a 
randomized block design with 4 replicates of 4 trees each. Although 
these young trees varied considerably in size and crop, the differences 
were somewhat equated between treatments. Oils 31, 35, 36, and 38 of 
Table 3 were used in both experiments and the second experiment uti- 
lized the same trees as did the first. The oils were applied at 1.5% 
concentration at approximately 5 gallons of spray per tree. 

The oils were prepared as described earlier and oil deposits were 
measured on both fruit and leaves by the same technique except for the 
method of sampling and size of the samples. Twenty- four leaves and 24 



47 

fruit were picked from each 4-tree plot immediately after spraying. 
The oil was removed by dipping each fruit or leaf in 2 successive 
dioxane washes. After the sample was collected, the 2 washes were com- 
bined for the spectrophotometer reading. Leaf areas were determined as 
previously described, but the surface areas of the fruit were measured 
by the method of Turrell (95). The major and minor axes of each fruit 
were measured and the corresponding surface area was obtained from a 
prepared table. 

Field Experiment No. 1: oil blotch, leaf drop, and fruit drop .-- 
The first experiment was applied on 6 May 1964, during the time the 
fruit sizes were in the range of 0.75 to 1.50 inches in diameter. The 
object was to induce oil blotch and to relate oil type to the incidence 
of the condition. Diameter measurements of 15 fruit on each of 40 
trees averaged 2.57 cm, or approximately 1 inch. Treatments were ap- 
plied with a "Speed Sprayer" Model 705 CP air-blast sprayer traveling 
at 1 mph. A large plastic shield was used to protect adjacent trees 
from the spray drift. 

The fruit were checked periodically on the tree for oil blotch. 
For 5 weeks after spraying, the rates of fruit and leaf drop were de- 
termined weekly. An area under each tree, extending to about 1 foot be- 
yond the drip line, was raked clean after spraying. One week later, and 
weekly thereafter up to the fifth week, the dropped leaves and fruit 
were collected. The fruit were counted but the leaves were weighed be- 
cause of the excessive amount of drop. 

Field Experime nt No. 2; fruit color and internal fruit quality .— 
A late-season application of 4 oils was made on 18 September 1964, with 
the objective of relating oil heaviness and refinement to effect on 



48 

degreening and fruit quality. Treatments were applied with a high- 
pressure sprayer and a double-nozzle hand gun. The plastic shield was 
used to protect adjacent trees from spray drift as in the above experi- 
ment. Fruit samples were harvested on 16 October, 1 and 12 November, 
and 7 December, or approximately 4, 6, 8, and 12 weeks after treatment. 
The samples consisted of 40 fruit from each 4- tree plot. Where possi- 
ble, the fruit were picked from the outside canopy of the tree at a 
height of 3 to 6 feet and both very large and very small fruit were 
avoided. However, due to limited quantity of fruit on some trees, some 
of the sampling, especially the fourth sample, was done without regard 
to fruit size or location on the tree, both of which are recognized 
sources of error, especially for fruit quality (69). Both the degreen- 
ing and fruit quality studies utilized the same fruit samples. 

Color measurement and ethylene degreening . --The first and third 
40-fruit samples were degreened for 72 hours with ethylene gas after 
harvesting. A 4 x 4 x 4- foot degreening chamber was used and commer- 
cial recommendations on temperature, humidity and ethylene gas concen- 
tration were followed (32). Degreening rates were determined instru- 
mentally, using the reflectance attachment of a Bausch and Lomb 
"Spectronic 20" spectrophotometer (33). The amount of green color in 
the peel was measured as per cent absorbance at 675 m|i. A 1- inch- 
diameter circular area was randomly selected and marked on the equator 
of each fruit and a color reading was taken in this circle after 0, 24, 
48, and 72 hours degreening time. The degreening rate was indicated by 
the decrease in absorbance from 1 reading to the next. Color measure- 
ments were taken 4 and 8 weeks after treatment. The coefficient of re- 
gression of per cent absorbance on degreening time was calculated for 



49 



each treatment, and these were used for comparing the effects of the 
various treatments on degreening rate. 

To supplement the instrumental measurements of the degreening rate, 
20-fruit samples from each treatment were degreened for the same time 
intervals and photographed together to illustrate the color changes 
visually. Twenty extra fruit were harvested from each plot at the 
same time as were the 40- fruit samples. The 4 samples from each treat- 
ment were mixed and then divided randomly into four 20-fruit lots. One 
lot of 20 fruit for each treatment was placed in the degreening chamber 
at the start of the 72-hour period, a second lot was added at 24 hours, 
and a third at 48 hours; the fourth lot received no ethylene degreening. 
Therefore, the 4 lots of fruit were degreened 72, 48, 24, and hours, 
respectively. At the end of the 72-hour period, the 4 lots of fruit for 
all 5 treatments were photographed together in color. These photo- 
graphs are presented with the numerical data. 

Fruit quality . --After the degreening treatments described above, 
the 40-fruit samples were analyzed for internal quality by standard 
methods (75). The analyses included the following determinations: 
per cent soluble solids (° Brix); per cent acid; Brix/acid ratio; fruit 
weight; juice weight; and per cent juice (by weight). Solids determi- 
nations were made with a Brix hydrometer and acid was determined titri- 
metrically with standard sodium hydroxide solution and phenolphthalein 
indicator. The treatments were compared mainly on the basis of per 
cent soluble solids. 



RESULTS AND DISCUSSION 

Relation of Composition and Heaviness of Oils 
to Insecticidal and Ovicidal Efficiency 

Dosage-mortality tests were conducted for selected fractions of 
the narrow-boiling paraffinic, reformed, and naphthenic series against 
citrus red mite eggs and adult female Florida red scale, and 30 com- 
mercial-type oils were screened against Florida red scale, in the 
laboratory. The properties of molecular weight, viscosity, 50% distil- 
lation point, and chemical composition or base- type (paraffinic, re- 
formed, or naphthenic) were studied with respect to control efficiency. 
A field application of 4 commercial- type oils gave some information on 
residual control of spider mites. 
Results 

Florida red scale studies . --Oil deposit, total number of scales, 
and per cent kill for each dosage level of the oils used in the dosage- 
mortality tests against Florida red scale adults are listed in Table 4. 
The LD5Q and LD95 values, their 95% confidence intervals, and slopes of 
the regression lines as obtained by probit analysis are presented in 
Table 5. The probit regression lines in Figure 6 show the dosage- 
mortality relationships of the various fractions in each series. The 
relationship of oil heaviness to efficiency in kill is depicted in 
Figures 7, 8, and 9, where LD95 values are plotted, according to chemi- 
cal composition, against molecular weight, viscosity, and 50% distilla- 
tion point, respectively. Efficiency varies inversely with the LD95 



50 



51 



s 






3 






a> 






i-i 






o 






u 






u 






(U 




■u 


a 




•1-t 
CO 


14-1 




o 


o 






(0 




•o 


(U 






•H 




? 


U 




o 


(U 




l-( 


«3 




o 


n 




J-> 


JS 




J2 


AJ 




t>0 


•H 




•I-I 


& 




x; 


1—1 


(U 


« 


r-l 


1— ( 


CO 


•T-l 


CO 


I-I 


^ 


o 


0) 




10 


> 


J-l 




(U 


c 


•o 


T-l 


(U 


0) 




o 


M 


0) 
tlO 


u 


cd 


to 


0) 


■o 


(0 


o. 


•iH 


o 




M 


Q 


Tl 


o 





CO 


CO 


(U 


C 


t-l 


•H 


CO 


to 


CJ 


00 


CO 


to 


y-i 


to 


o 


4-1 




CO 


u 


d) 


0) 


U 


^ 






P^ 


3 


u 


c 


•H 




1—1 


•V 


CO 


*J 


4-> 


•H 


U 


CO 


o 


o 


B 


a 




<u 


<u 


•o 


00 




CO 


I-I 


CO 


•I-I 


o 


o 


-o 


• 




«* 




cu 




1— 1 




XI 




to 




H 





<3\ 



00 



in 



en 



CM 



O 

CN 



tM 



a 

o 

bO 



CO f-l 

Q) i-H 

l-H •!-! 

to ^ 
o 







vO 






VO 






vO 






VO 






VO 


o 


00 

1-1 

CO 


in 


o 


00 

1-1 

fO 


in 


o 


00 

1-1 

CO 


in 


o 


00 

t-l 
ro 


in 


o 


00 

1-1 


m 



O vO t-H 

CO 
00 



vOOvCM mOOOO <tr-~0 P-»0OCM 0OCSC>4 

CMi— I 1— IvO 1— lOOi— I 1— l»d"i— I i-<i-li-4 

ro .vt CO «* CO 



o c^ CN 


vO t-l O 


O 


CM 0^ 1-1 


CM 


CM 



l-» 1— 1 o 


vD r~. O 


vO i-H [^ 


r^ O CJ^ 


CN CO i-H 


O CO l-H 


r^ vo CN 


r^ 1-1 »d- 


CM in CTi 


CO vO CM 


CM I-I CN 


CM 1-1 -* 


CO O CO 


CO vj- r-l 


CM CM 1-1 


CO CO vO 


t-l 


CM 


CO 


CO 


CO 


CO 


CM 


<M 



o 1-1 r^ 


co<3^ 1-1 


13^ r-- CM 


1-1 CO 00 


vo <N m 


vo CM in 


o 


1-1 r~ 


CTv CN 00 


>d- vO r-» 


in 00 a\ 


CO o 00 


<)■ in C3N 


-d- vO vO 


>* c:n in 


«* 


vO 1-1 


<t -ct 00 


CO 


CO 


CO 


CO 


CO 


CO 




CM 


CM 



-d- t3v ^ 


.-ip^ -* 


o 00 •* 


.* O 00 


CM 1^ CM 


CTv .^ 1-1 


<j- vo m 


CM >* CO 


in m 00 


p^o a> 


in CM CTv 


in o cjv 


vO CO CTi 


m CO <3v 


m r>- cTi 


vO vD 0^ 


1-1 


CO 


CO 


CO 


CM 


CM 


1-1 


CO 



r^i-Hvo oomo cooovo cjvp^on oooo i-io\vO r>-co»* f^r»«o> 

vOCNOO OOvOO ^ y£> (y\ vDC3^C3^ P»^CMr^ r».00Ov vOinCTi 00O^O^ 

CM CMi-H<* CM «* >-l CM CN 



r-l <r CM 


incN 00 


r^ vo o> 


CO vO ON 


ov vO 00 


-* 


1-1 «n 


I-I r^ CM 


1-1 


in ON 


00 t-l o\ 


C7V vo <yi 


00 CM Ov 


00 m <3v 


r-~ 00 C3V 


CTv 


oo cr> 


CO o cy> 


o 


00 <Ti 


CN 


CN 


CM 


CM 


CM 




CO 


CM 


1-1 


CM 



>^Ooo r^oooo <l-r-.o t-icoo ctvooo inr~-ON •<fvoco cMino> 

<yvOOCJ> OvOCJv CJ^lnO OCOO OOCOO C3vr>.ON ONCOCTv ocoon 

1-1 i-HCO COrHi-ICMi-H COt-l CM CO r-HCM 



00 


o in 


in 00 vo 


0^ 


ON O 


in 


o 


o 


CM 


in o 


1-1 


vo a\ 


00 


<N l-H 


OO 


vO 


o 


o 


CM 00 


1-1 r^ ON 


1-1 


o o 


o 


C3N 


o 


CM 


r-H O 


CM 


r~ ON 


o 


00 c^ 


iH 


m 


o 


t-l 


CM 


1-1 CM 


t-l 


CO I-I 


1-1 


CO 


t-l 


t-l 


CO 1-1 


1—1 


CO 


fH 


i-H 


i-H 


CM 


1-1 



CM CO 1-1 

e (u 1-1 

U i-H •iH 

^~. to ^ 



CM 



to f-l 

<U I-H 

I-H -H 

to ^ 
bO cj 



a 

tj 



CN 



CO 

(U 



a 

u . . 

•^ to 

00 CJ 



CM 



CO 



a 

o . . . . 

— CO j<; 
00 u 

i w s-s 



CN 



CO 



a 

o . . .. 
^. to ^ 

00 u 



CO I-H 

(U 1—1 

•H 

- to X 
00 u 
H. W frS 



a 



CM 



a <u 

O t-H 

~^ to 
00 u 






m 

vO 
CM 


in 
00 

CM 


in 
o 

CO 


o 

IN 

CO 


m 

vO 
CO 


CO 
•* 


CM 


m 
eo 

CM 


iL 


1 


1 


PU 


1 

PL4 


1 

ft* 


ik 


Pi 



52 



vO .-1 


O VO .-1 


O vO 


CO 


rn 


CO 


n 


n 


en 



O vD O- 



o \o ■<)■ 



o vo «d- 

CM 



O vO .* 
<)• 
csj 



ovo«d- 

<N 



00 



in CO in 


VO O r«. 


vO Ov 00 


O Ov CM 


00 r-- o 


in 00 vo 


>* 1^ si- 


00 O C3N 


voincM 


.-H in 


.— 1 O ■— 1 


r-l CO 


O 


CM VO cvj 


^ CO 


.-1 eg 


.-1 o 


t-l Ov f-l 


CO 


CO 


CO 


CM 


CN 


CM 


CN 


CO 


CM 



.-1 o cj> 


1-1 ^ CM 


CO vO vO 


1^ VO CN 


0^ CO VO 


r~. m r>- 


<Ti m i-i 


CO r~. .* 


CO 00 vO 


CO CO lO 


CM <f 


CO CJ^ CM 


CM in 


CM O CM 


CO 


CM 


CM 


CN 


CN 


CM 


CM 



(0 

o 

a 

o 



00 vo m 

<j- m cTi 

CM 



CM r-» CO vO vOsf 

CO vo in CM m CO 

CM CM 



O 00 CM 

m <J- C3^ 
CM 



o in «* 
in 00 ov 



O ON 

<r CM 

CM 



CM CM 00 

m CM r^ 

CM 



--I «* vO 

>* vO vO 

CM 



CM vO vO 

>d- CM t~- 

fO 



m m CM 
in CO 00 

CO 



00 r-l CM 

co>-H r-v 
CM 



•H 



o 00 00 


CM o 00 


r-~ vO CM 


<J- 


in o 


CO <!■ CO 


i^ i-i in 


■* 00 in 


CM vo O 


O00r-( 


r- 1-1 ov 


vO O <Ti 


vo CO C3^ 


m 


o <f 


vO ,-1 ON 


in r^ cjv 


vO rH CJN 


vO CM CO 


inm CO 


CO 


CO 


CM 




CM 


CO 


i-i 


CM 


CM 


CM 



(U 

> 



60 
CO 

o 
a 



00 00 o> 


O 00 <Ti 


o ON 00 


r-~ O CO 


o r^ 


CO 


ON CO vO 


r-f P>. 00 


O CO vO 


Oovr^ 


r- CO C3V 


1^ in CT> 


r^ vo C3N 


vo CO r~- 


r^ m 


ON 


VO 1-1 ON 


r~. in ON 


00 i-< CJN 


r- oocJN 


CM 


CM 


CM 


r-l 


CM 




CO 


CM 


CM 


r-l 



CM ^ 


O 


CM CJN CT^ 


00 vO ON 


r-l vo CJN 


00 vO CM 


r-» CO P-- 


o 


ON ON 


vo o in 


o 1-1 r~- 


C3N ^ 


O 


ON -d- 0^ 


ON m ON 


CO St 00 


00 <}• ON 


00 CM ON 


ON 


CO <JN 


0^ 1-1 ON 


O P^ON 


CM 


1-1 


CO 


CO 


rH 


CM 


CM 




CM 


CM 


1-HCM 



CM 



St O CJN 


o 


00 CTN 


vO 


ON 00 


-* 1^ vO 


CM 


CO en 


vO 


CO ON 


CM m 


o 


r-l 


in 00 


ONCM O 


ON CO ON 


o 


O ON 


O 


r-l ON 


ON rH ON 


O 


CO ON 


ON 


oo ON 


CTN CM 


o 


r-l 


ON ON 


OCOO 


CM 


r-l 


CO 


r-l 


CM 


r-l 


r-l 


CM 




CM 


CM 


r-l 


<-t 


r-l 


r-l CM r-l 



in m o CM r-l CO 
ON in o o o ON 

CM r-l r-l CM 



o 


-* C7> 


00 


CO CTN 


CM 


r~ 


o 


o 


00 


o 


r-l 


r-l 


o 


CO 


r-l 00 


OvtO 


CO 


r-l ON 


o 


in 00 


CM 


in 


o 


r-l 


-* 


o 


r-t 


t^ 


o 


r-l 


00 ON 


CMrHO 


r-l 


CO 


r-l 


CM 


r-l 


CM 


1-1 


r-l 


CO 


rH 


r-l 


r-l 


r-< 


r-l 


CM 


rH CM r-l 



3 



C 

o 

u 

I 

I 

St 





■ — ^ to j^ 

ZL W S-S 



1-1 CM 



01 

lU 



B 

o . ■ . . 

— td ^ 

00 o 



icn 



CO 
0) 



CM CO rH CM 

e (U rH B 

t) rH .iH U 1-1 .H 

CO ^ -», CO ^ 

00 0) tjp O 



iCfl B-2 



N CO rH 

e 0) rH 

O rH -iH 

-«^ to ^ 

60 O 

i CO g~s 



CM 



o •-> 

■^ to 
(JO o 



CM 



CO 
(U 



s 

o . . . . 

-^ CO jii 
00 u 

i CO B-S 



M CO 

B <u 

■^ CO 

bO U 



CM CO rH 

B <UrH 

CJ rH -rl 

^. tO;^ 

60O 

ico^s 



XI 

to 

H 



m 
o 

CO 


o 

CM 

CO 


m 

vo 

CO 


m 

vO 
CM 


in 
00 

CM 


in 
o 


O 
CM 

CO 


m 

vO 

CO 


in 

ON 
CO 


Pi 


1 

PCS 


1 

cm 


15 


1 


1 

13 


1 

iz; 


;s 


1 

2 



53 



Table 5. Effectiveness of 3 series of petrolevim oils against adult 
female Florida red scale^ 





Slope of 
regression 


^^50 


, ng/cm 


2 


LD95 




, lig/cm'' 


















Oil 


line 


Dose 


957o 


CL 


Dose 


95% 


CL 


P-265 


3.389 


30.0 


• • ~ 


• • 


91.1 


• • 


_ 


• • 


P-285 


6.932 


43.9 


15.7 - 


60.1 


75.8 


56.1 


- 


385.2 


P-305 


6.420 


31.4 


26.8 - 


35.2 


56.7 


50.2 


- 


68.4 


P-320 


5.944 


31.3 


25.6 - 


35.5 


59.2 


51.7 


- 


74.2 


P-365 


5.420 


41.9 


27.8 - 


50.7 


84.2 


69.1 


- 


130.8 


P-435 


6.758 


45.5 


35.8 - 


52.9 


79.7 


67.1 


- 


112.8 


R-265 


5.189 


43.9 


• • ~ 


• • 


91.0 


• • 


- 


■ • 


R-285 


7.030 


35.9 


30.6 - 


40.6 


61.5 


52.8 


- 


80.8 


R-305 


6.635 


30.5 


25.7 - 


34.3 


54.0 


47.1 


- 


67.8 


R-320 


4.703 


26.2 


22.3 - 


29.8 


58.6 


50.6 


- 


71.3 


R-365 


4.649 


30.6 


25.6 - 


35.3 


69.0 


58.6 


- 


86.3 


N-265 


6.818 


58.0 


• • " 


• • 


100.1 


• • 


. 




N-285 


6.409 


43.5 


34.0 - 


50.6 


78.6 


66.3 


- 


109.6 


N-305 


7.117 


39.2 


32.4 - 


44.8 


66.8 


57.4 


- 


87.2 


N-320 


7.174 


36.1 


31.9 - 


39.5 


61.1 


54.6 


- 


72.9 


N-365 


4.300 


35.6 


30.4 - 


40.2 


85.9 


74.9 


- 


103.4 


N-395 


4.542 


31.8 


27.8 - 


35.5 


73.1 


63.5 


~ 


88.5 



^Values for slopes of dosage-mortality regression lines and 95% 
confidence limits (CL) for lethal doses (LD) for 50% and 95% kill 
were obtained by probit analysis. Confidence limits were not cal- 
culated for the lightest fraction in each series. 



54 



7 


1 1 

NAPHTHENIC 


1 


r ' 1^ 1 


6 






^^^^^ 


5 


t;-^ 


^^^^^ 


^^^^ : 


4 


"''^^^'''^^^'''^'''^ 


^^''^''^ ' :' ■ 


- 



98 
95 



- 85 

- 70 

- 50 

30 
20 

- 10 









W 
Cd 

o 







OIL DEPOSIT, iig/cm^ 



t 

H 

pei 
O 

P^ 



Pm 



O 

•J 
1-4 

M 



H 
U 

W 
PM 



Figure 6. Regression of per cent kill on deposit level for 3 series of 
narrow-boiling petroleum fractions tested against adult female 
Florida red scale. The number on each line indicates the average 
molecular weight of the fraction. 



55 



T — ' — I — ' — r 



T 1 1 1— r 




J L 



o 



o 

CM 



o 
o 



o 
00 



o 



o 

M 



t3 



o 
in 



<u 

r-l 

o 

M 

4-> 

0) 
Q. 

bO 



o 

o 
u 

\& 



M-l 
O 

CO 
(U 
•rt 

cu 

CO 

en 

u 
o 



00 <u 



?6r 



niD/grl '^Oqi 



o 


§ 


(U C0 

3 o 


ro 


M 


M 




O 


CO TD 




^ 


.-1 (U 
3 Vj 




W 


o 




> 


(U CO 




< 


r-l 73 


O 

CM 




9 '"^ 


c> 




O .-1 

C 0) 

•H CO 


o 

O 




4J B 
CO <U 


CM 




r-l 
C 3 

CO 


O 




o u 


00 




C CO 


CM 




Efficie 
s again 


o 




c 


CM 




o 
(U CO 
Vj U 
3 u-i 
00 



J- - 1 V a 



56 



1 ^ 1 T 



o 

CM 



O 

M 

M 
1^ 



^ 



o 



o 
o 




o 
in 



o 



O 



I 

U 
« 

i 



o 




0) 


o 




I-l 


(N 




o 
u 
■u 
w 
p. 


O 




c 


00 




•H 


1-1 




r-l 
•H 
O 

X) 


o 




M 


vO 




h 


.-1 




to 

c 




fa 


M-l 

o 




o 






o 


0) 




1—1 


a> 


o 




•H 


<t- 


H 


u 


I— 1 


!=> 


<u 

03 




en 


CO 




CO 


n 




" 


o 


o 

CM 


S 




I— 1 


M 


>^T-I 




WJ 


4J lO 




O 


•<-l o 




U 


(0 U3 




W 


O 




M 


u "o 




> 


en (u 


o 




•rl ^1 


o 




> 


I-l 




tion to 
Florida 


o 




CI) 0) 


00 




r-l 1-1 






(U CO 



H 



UID/Sli «^6g^ 



4J 
CQ 

c 

•H 

CO 
00 
CO 



00 OQ 

c 
« o 

a "^ 

bO 



57 




I L 




1 ^ \ r 



o 

o 



s 



s 



o 

I*. 



o 



o 

GO 



O 



O 



O 



O 
o 



o 

00 
vO 



o 



O 
vO 



O 



H 
O 

o 






o 

in 



o 
in 



00 

c 



o 
I 



1^ 
1^ 
cd 

C 

O 

CO 
<Si 
•rA 
U 
(U 
CO 

CO 

u 

o • 

V4-I O) 
4-> Cd 

c o 

•H CO 

o 

c M 
o 
•H Cd 

4J T3 

Cd -r^ 

■-H H 

.-I O 

•H 1-1 

•U Pn 

CO 

•i-l <u 

X) r-l 
td 

6^ B 

o <u 
in n-i 

o -u 

4J r-l 

>= "2 

O cd 

•i-i 

4J U 
Cd CO 



Cd 

bO 
Cd 



mo /Sri '^^ai 
c 





(0 


>% 


C 


o 


o 


c 


•H 


<u 


^ 


•H 


U 


U 


(0 


•i-l 


M 


U-t 


14-1 


14-1 




U 


g 




0) 


• 


t-< 


(3^ 


o 




H 


CU 


+J 


k 


(U 


3 


D- 


00 





Eli 



58 

values. The relative efficiency of the 3 series, in decreasing order, 
was reformed, paraffinic, and naphthenic. Efficiency increased with 
heaviness up to a point, after which the trend reversed. The points of 
maximum efficiency of the 3 physical properties considered for the dif- 
ferent types of oil were: 

1) Molecular weight--paraff inic, 305; reformed, 305; and 
naphthenic, 320. 

2) Viscosity, SSU at 100 F--paraf f inic , 59.8; reformed, 
59.3; and naphthenic, 79.7. 

3) Fifty per cent distillation point--paraf f inic , 696 F; 
reformed, 700 F; and naphthenic, 689 F. 

A practical deposit level of 70 ng/cm^ was selected as the maximum 

deposit for efficient kill of scale insects. The following minimum 

physical property values were derived by this criterion from the curves 

in Figures 7, 8, and 9: 

1) Molecular weight--ref ormed, 279; paraffinic, 291; and 
naphthenic, 300. 

2) Viscosity, SSU at 100 F--reformed, 51; paraffinic, 53; 
and naphthenic, 66. 

3) Fifty per cent distillation point--ref ormed, 644 F; 
naphthenic, 657 F; and paraffinic, 661 F. 

Thirty commercial distillation range oils were compared at 0.5% 

and 1.257o concentration. These oils represented 5 viscosity classes: 

60, 70, 80, 90, and 100 SSU at 100 F. Oil deposit, corrected per cent 

kill for each replicate, and mean per cent kill for the oils at each of 

the 2 dosage levels appear in Table 6. Although arranged from high to 

low kill in each viscosity class at the low dosage level, the data were 

analyzed together. Therefore, the letters denoting significance apply 

across all viscosity classes under a given dosage level. Levels of 

kill were quite variable within each viscosity class at the 0.5% dosage 



59 



(U 

X) 
•H 

O 

,-( 

(U 
i-H 

cd 

S 

0) 



3 



CO 

C 

•rt 
CO 

bO 
tfl 

C 

o 



CO 
U 

•r-l 

a, 
a 

CO 



o 

CO 

I-l 

> 



CO 
CO 



u 



O 

CO 
OS 
41 

e 
> 

•H 

4-1 CO 

U Q) 

(U .-I 

M-l CO 

>4-( U 

W to 



•8 



o 
m 

CM 



CO 

C 

o 



<u 



CJ 

a 



in 



n 



CV) 



■PCS 

•H a 

CO u 

o ^ 
Q 



S 



o 
in 



•t-i 



CO 

C 

o 

•1-1 

4-1 
CO 

u 






n 



•UCN 

•H g 

CO u 
O — 

Q 



fe 



>,o 


4-1 


o 


•H 


i-H 


CO 




o 


4-1 


O 


CO 


CO 




•H 


& 


> 


OT 




CO 


1— 1 


• 


•1-1 


o 


o 


z 



^ U3 ^ CJ U 

CO CO CO CO CO ^ ^ 



O O O 

^ XI ^ ^ J3 XI 43 
CO CO CO CO CO CO CO 



J3 ^ 43 X3 
CO CO CO CO 



U U CJ 
^ X3 X3 43 
CO CO CO CO CO 



CO o to 



a\<j-vOi-HOonfM inin.-irofOinininovor~ car^Osto^ <T>fnc» 



vo r^ ctn o^ o vD ^o 

CT* On CT^ ON O cy* 0^ 



O C» O O O I — 1^ 
O cy\ O O O CJ^ 0^ 



O O O O O CX) r^ 
O O O O O CJ^ tJN 



•^ cx) o cTi o m i^ 

CTi 0^ O 0> O CTi CJ> 



C30 CM O r^ O l~^ 1-1 
(Ti C3^ O CTi O CTi CJN 



CM 00 00 o o >d- o> 

CTn C3^ CTn O O CT\ CTi 



r^ vD I-l 00 •<^ n r^ 
CO r^ O vO r^ C3^ 00 



X) "O 14-1 

o o 



oooor^ooo^vOvoo^o^v00o 
t3^<3^C3^t3^C3^CJ^CT^CJ^CJ^C7^e3^ 



OOOrOOOOOOOvDOO 

o<yi<r^oocy\ooo>oo 



00 O CJ^ O 

cj> o cr. o 



CTi O CO o o o o 
C3^ O (TN O O O O 



0^l — r^t-~r~» OOCT>00 
<3^0^e?^C3^e3^ cyiOOtT* 



O O O O CM 0-*0 
OOOOCTi OvOO 



OO<*0000 OOO 
OOCJ^CT^O^ OOO 



c3^O00vOO00r~CJ^O^O^-. 
O^Oa^<?^OCOCJ^e3^0^00^ 



00^0^^^<J^OOC3^0CMOO 
OC3^C3^0^0^000^0C^^<3^ 



^O^r^O^O^^-.c^O^Ol— tON 
CJ^<J^o^c3^CJ^CJ^e3^cJ^oc3^CJ^ 



oon I cn>d-in»*.^p>.foo 

0000 0000O^00O^0000^~ 



"W MM 

eU 4-1 (4-1 IM M-l 

'O O QJ V Q) 

O 73 "O "O -O 

XI tJ O (J O 



o 00 CO 00 o 
O CJN ej\ (Ti o 



o^ <yi r^ 

CT\ 0^ On 



OCTiOCMO OOOOO 
OCTnOCJnO OOOCTv 



O^CM^o<J^O vOvOO 
cjNCTNCTieyiO cjNCTiO 



rn CM 00 CM 00 

O 00 CJN CJV <T\ 



00 1^ r~. 





m m 


M 


0) 0) cu 0) 


14-1 


-O -O "O -O T3 


0> tH 


o o o o o u 


T3 x: -1-1 


.C X5 X> X3 X XI 


O M42 -i-t -H 


CO to CO CO CO to 



(U (U <4-l bO M 

tJ "O 0) M-l M iH 

u o "o 0) M-i 4) x: 

COCOXO'O tOyit^ 



cjNr~-oo.-ivOi-(^ intNinvomror^cTNinoocyi r^.oocn.-40o <y\0\r-i 



00 -^ m n m 00 cN 
r^ r^ m CO CM CM CM 



<f O CM vO 1-H CN VO 

r~ i-~. m CM 1— I -^ 



00 CTv vO 00 "^ r^ 00 
00 vD m CM CM 1-1 



CO 00 t^ O CM O CJ^ 
00 00 <t CO CO CM CM 



sj- vO r^ r~. ^ m v£> 
vO vo r~. CM m -d- 



in o m <t i~^ CM vo 
00 00 -* m m 



>* CM 1-4 O CM o >* 
CO •<!■ CO CO CO St CO 



cTi^i-rHinincoocyioor^vo 
I t^i^vovO'^voinininm 



v0^nc3^vOCMl— lOCTiincMvO 

ooooint^oovof^incovom 



•— ICMCOO>OOCMVOCJ>CMCMCM 
00<3N0000in<fcO-^~^vOvO 

r^oocMcOi-iinooooinincM 
ooincovop^vooor^-m^vo 



invovocTNcocoincyiooeTi.— I 
vOvDvocoinoo<tinr--r>.in 



Oi— loor— icovommi— icMco 
oor^\ovovovovoinoo*^in 



CO CO 



cTi^oorOi— icjnooo 

CNCOCOCO«*CO»;t<M 



O m CM f^ «* 

r-. vo vo m m 



«* f^ <!■ CM CM 

vO o^ \0 in vO 



cN m o CM o 
r- ^ m in r^ 



O o r^ CO r^ 
00 r^ in vo <t- 



>* vo <t o <!• 
vD m vo vo in 



<)■ 1-1 vo cyi CM 
r^ vo r^ m -* 



1— I o in 1— I vo 

CO CO CO -* CO 



i-H vO r-l 

ooin<f 



o invo 
o^ com 



mo 00 

CJ\ vO 1-1 



•<t<Ns;l- 
C3^ m-J- 



StOOvO 
vO vO CO 



r~- 0^ CN 

vo vo m 



v£) r^ O 
Sj- CM CO 



Ovooooovooo voomcocMOmt^vocJ^m 



O p~- 1— I r-- r~~ r~- 00 
vo m vo m m m m 



vOmv£><t-*CMOi-ICTNvO\0 



r^vomCTNm moo 

• •••• ••• 

^CTistCOvO CMCMCM 

oor^oooooo a\ cr\<y\ 



% 



m 00 r^ CM CM <t CO 
m CO sj" m m m m 



% 



^CMi— li— Iv^i— ICTivOOOmi— I 

•^••vtmrocovtfoco^N^m 



CTi O CM CO CTi 

CM CO CO CO >d- 



moo 
com m 



60 









o 


_ _ ^ CJ 








4-1 






s 


CO CO eg ^ 




•o 




3 






A 






(U 


■u 


O 






^ 


vo o ^ n 




•o 


CO 


JZ 






s 


• • • • 




c 




4-1 








o^ o o^ m 




3 


4-1 


•H 








0^ O ON 0^ 




o 


a 


IS 








I— ( 




to 


0) 


CO 

u 










o o o o 




<u 


M-l 


0) 








m 


o o o o 




3 


y-i 


^ 






^ 




I— t »— < I— 1 1— 1 




rH 


•1-1 


s 






.-1 








to 


■a 


3 






f— 1 








> 




a 






•l-l 




O O r-~ (N 






>, 








^ 


>d- 


o o <yi C3N 




0) 


I— 1 


bO 




.—1 






^ i-H 




4J 


4J 


c 




O 










CO 
O 

•rt 




•H 




B~S 


to 




00 O o\ r-> 




1— 1 


•H 


O 




m 


g 


tn 


CJN O ON C3N 




a 


M-l 


a 




es 


O 




.— 1 




<u 


•r4 


CO 




• 


•i-t 

cd 




O O O ro 




PtS 


•H 


0) 






u 


CVJ 


O O O C3N 




• 


CO 


o 






ft 




r-H ,-1 r-l 




CO 




tj 






i-i 








1-1 


4J 








a. 








3 


O 


<u 






Si 




o o o -* 




a 


c 


JZ 






Pi 


1-4 


o o o cjN 

r-H .-H I-H 




u 
o 


(U 


4-1 












M-l 


13 


x> 






J-JCM 






CO 










•-• B 








U 


•o 






CO (J 






J-l 


0) 


a> 






o -^ 


o> r~- r^ VO 


• 


4J 


4J 


4J 






a (so 


00 (» o ON 


t3 


o 


4J 


o 






<u i 


1—1 


CO 


^ 


<u 


C 






Q 




M 


:§ 


rH 










O 




(U 










<4-l 
lU 0) 


O 

.—1 


o 

4J 


a 4J 


CO 

r-t 








•O TJ 






CO CO 


•M 








O U 


T3 


bO 


0) 


o 








- -S -9 '^o 

CO CO CO (4-4 


§ 


C 

•H 


(U H 

x: 


<U 






r^ I— 1 C3N 1— 1 


O 


•a 


4J 0) 
00 


:S 






S 


• • • • 


CJN 


o 


^ « 










-* O CM 00 




u 


•4-1 








00 r- vo •<)■ 


•* 


u 


Bd 


o 






^ 






o 


CO 


x) 








r— * 






00 




0) 0) 


CO 






.-1 


m 


O «* O vO 




M 


U fH 


a 






•i-l 




<3N vO vO CM 


rv 


>^ 


5 a. 


o 






X 






o 


4.1 
•H 


r-l -H 
1-1 4J 


•I-l 

4J 




r-H 


B~S 


<J- 


CM 00 n CM 




1—1 


O 1-1 


CO 




•fl 






00 vo r^ r-~ 


n 


CO 


14-1 3 


1-H 




o 


•^ 






o 


u 


a 








CO 






vO 


u 


1—1 


)H 




B~S 


C 


en 


<7^ O 00 O 




o 


(U ^ 




O 


o 




r^ 00 <J- <J- 




B 


> s 


O 




m 


•H 






• • 




<U 2 


<4-l 




• 


■U 






CO 


1—1 


I-l 






o 


to 


tN 


CO 00 00 CO 


0) 


CO . 


CO 


1-4 






o 




ON r^ vo lA 


CO 


M c 


<u - 


CO 






•f-t 






CO 


3 O 


^§ 


•H 






f-H 






CO 


•U -H 


o 






a. 


r-l 


O ON vo o 


.-1 


to 4J 


CO u 


u 






a: 




00 in vo m 


u 


C CO 


o c 


01 












•u 


t3 3 












>. 


M C 


Q 


B 










4J 


O <U 


C 


O 






■UCsl 
•rl B 




•fl 


M-l CO 


(U o 


U 








CO 


(U 


> -u 








to O 




O 


■O M 


•H 


(U 






o ^^ 


00 00 o 1^ 


o 


<u a 


bO 00 


13 






O. 00 


n ro .^ CO 


CO 


•u 


c 






<U It 




•1-1 


U M 


to •S 








Q 




> 


0) o 


TJ 


- 










U 14-1 


4-^ U 


"cO 






m 


IH 


CO O 


2 


(^ 






O CO 


u 




■u o 




C 
1-1 


o u 

1-4 XI 


CO 


>N 

J3 


4J 

c 
o 


•w I— 1 




T3 


1—1 g 


(U 1-1 


"O 


CO 


O O rH o 


(U 


•H 3 


S (U 


0) 


o w 


• • • • 
in o CM en 





j<i a 


4J (U 


4J 

o 


1 


(0 


O O t-l o 


o 


i-> <u 


C '-I 


C S 


1 


•H t3 


I— 1 1—1 I-H r-H 


^ 


C '-I 


(U 


4) 


^o 


> M 




M 


cu o 


B 5^ 


•a CO 




C/3 




CO 


"-§ 


4J m 

CO 


CO ~ 


H 




•H 

o 


^ 


n o p^ vo 

«* •* CO «;!• 


1—1 

•H 
tP 


0) o 
J3 


(U (1) 

M x: 

H 4J 

o 


*Oil 
the 



61 



level. None of the oils attained 95% kill at this dosage; however, the 
deposits were considerably less than the lowest LD95 values obtained 
in the dosage-mortality tests. On the other hand, only 1 oil, No. 50a, 
failed to give above 95% kill at the 1.25% dosage level and this fail- 
ure can be attributed to the low level of kill obtained on replicate 
No. 5. The deposits obtained were all as high or higher than the 
70 ng/cm level discussed above. Correlation between oil viscosity and 
scale kill is not apparent from the data in Table 6. However, the 
viscosity range covered by these commercial oils lies well within the 
effective range for viscosity as indicated in Figure 8. 

Citrus re d mite studies . --Oil deposit, total number of eggs, and 
per cent kill for each dosage level of the oils used in the dosage- 
mortality tests on citrus red mite eggs are listed in Table 7. The 
oils are identified by name in the table. The results of the computer 
analyses are presented in Table 8. Certain of the LD95 values had 
rather broad 95% confidence intervals but this was due in part to an 
excessive number of points occurring above this level of kill and per- 
haps to the fact that the various points were run over a period of 
several weeks. Although the confidence limits were wide in certain in- 
stances, LD93 values were found to be quite reproducible. In subse- 
quent tests in which 10 concentrations were applied on the same day, 
LD95 values obtained for the P-320 and P-365 fractions were 16.4 and 
17.0 i^g/cm , respectively, with confidence intervals of 13.4 to 26,1 
and 10.5 to 46.6, respectively. The confidence limits varied somewhat 
from test to test for the same oil but the LD95 values were quite close 
in terms of actual oil deposit. 



62 



I 

0) 
CO 

o 

c 



•r-l 

o 

1-1 
o 
u 

4-1 



IW 




o 




CO 




0) 




•H 




M 




(U 




CO 




n 




ji 




4-1 




•H 




& 




t-l 




1—1 




•H 


CO 


,^ 


60 




60 


4J 


CD 


c 




0) 


QJ 


u 


J-) 




•r-l 


u 


B 


<u 




O.T) 




<u 


•a 


M 


§ 


CO 




S 


»* 


^1 


CO 


4J 


60 


•H 


W) 


O 


0) 






4-1 


IW 


CO 


o 


a 




•H 


n 


cd 


(1) 


W1 


^ 


to 


3 


CO 


c 


4-1 




CO 


" 


<U 



CO >. 
O 4J 

a -H 

0) i-l 
T3 £d 
4J 
>-< H 
•H O 

o e 



1^ 



■s 



n 



m 



O CM 



O CM r-H 



en 1-1 cNj 

u-i vo 



O CM 



CM ex3 O 



•H 
CO 

o 

0) 
XI 

o 



o 

4J 

60 
•H 



> 



60 
(0 
CO 

o 
Q 



(» 



o 



CO 



O- r^ 






CO CM 

•4- 



CO 

00 



O CM 



in -* CM 

Cvl c» 



vt r~ C3^ 
i-< vO CX) 



LO 



CM 



O O CM 
CO 



vo in o 

1-1 O 1-1 



CM 1-1 ON 

>d- CO 






■-I 00 CM 
iH O CO 



<f CM 00 

CM r~ CO 

.-I CO 



m 1-1 m 

CO CM <f 



O O CM 
CO 



c» in <j\ 

.-I o 



CM vt <i- 

CO O CO 

St 



CO CO i-< 

<f ■* <r 



-* O 1-1 
r~. 1-1 r~. 



O r^ r^ 
<3N 00 m 



O O CM 
CO 
vt 



O CTi o 

CM 1-1 CM 

<t 



in -* <J- 

CN 00 CO 
CO 



vo CM O 

CO C3N 00 

CO 



m CM in 

<f 1-1 00 

•<f 



00 o in 
f^ m <Ti 



vo 00 CM 

«d- vo 



«* Cvj CJV 

r-l r^ vo 



t~. 1— I C3> 
1-1 CT> 00 

•<^ 



o <)■ o 

CN OO CTV 



o CO 00 
CM in cjv 



CM t^ cyi 

•* St- t3N 

in 



00 CO vo 
CO 00 

St 



CTi CTi 00 
<* VO 



CO CM 1^ 

1-1 o 00 
m 



i-l vO 

00 cjN 



00 



1-H r^ 



vo -^ o 

CO vO O 
•<t 1-1 



00 CO o 

•* <t- o 

<t- ^ 



1. 



oo r-- .-I 
O cTv r~. 

1-1 CO 



1-1 r^ cyv 

CM CM CJV 

r-l <t 



00 <»• 00 

00 1— I <Ti 
•d- 



m C7N 00 

-d- 1-1 CTV 



<!■ O <Jv 

00 1-1 o 



m CO vo 

r-t 00 
St 



00 -vt in 

VO CJN 



vO CO vO 
1-1 ^i- ON 



00 CO 00 

1— I P- CT\ 

sJ- 



1-1 in 00 

CO 1-1 ON 

m 



r~. r^ <jv 

<f ON ON 



00 -* <JN 
<t CO ON 



00 CTN p^ 

r~- St C3N 



vo r~- 
1-1 St 



C3N r-l vO 
1-1 CO CT\ 



CO CM r-» 

CM m cjN 

<t 



vo CM m 

CM O ON 

in 



00 1^ vO 
CO 00 Cjv 

St 



00 r^ 1^ 

^ CTv ON 
St 



o CM 

St 

St 



O vO vo 
1-1 O vo 



in 

ON 
CO 



CO O vO 
r-l St r-. 



oo CJN CO 
1-1 CO oo 

St 



i-< vo r^ 
CM in oo 

St 



vO ON vO 
CM CM 00 

St 



CM -d- I^ 
CO vO 00 



CM St vo 

St P~ 00 

St 



00 CM m o CO in 

m CO ON m 00 ON 

St >* 



CM 

B 
o 



CO •^^ 
- 60 M 
60 60 
i W S~2 



O 

m 

CM 
I 



CM 

5 
o 



CO T^ 

- 60^ 
60 60 
n W S-2 



m 
vo 

CM 

I 

PM 



CM 

B 
o 



CO -H 

- bOM 

60 60 
i W S~2 



in 

00 



^ cv) 

■> B 

CO -1-1 u 

-•- 60^ --- 
60 60 
i W S-S 



S 

o 



CO .H 
- 60J«J 
60 60 
i W B-S 



CM 

B 
o 



Pk 



in 

o 

CO 

I 

PL| 



O 
CM 
CO 
I 
PL| 



CO -H 
- 60,ilJ 
60 60 

i w 6-a 



m 

vO 

CO 
I 

Pl4 



CM sd- o 

00 >t o 
sh 1-1 



E r-l 

O CO -H 
^^ 60^ 
60 60 
i W &^ 



in 

CO 
St 

04 



m m CJN 

00 00 ON 

St 



CM f-l 

t» CO -H 

■^ 60J«! 
60 60 
i W S-2 



O 
CM 

m 
I 

Ph 



63 



I I I III III I 



o .-< 04 

vO 



I I OcyiCM 1000 OCJNCN 

vrt <f vo IT) 
St -^ >* 



CM vO sd- 


vo 00 <f 


<t -* 


r^ CM 


00 ^ 


r^ 


-* 


^ 


in 



o 

a. 

(U 

o 



60 



00 



CM 

O CO ro 



cy> o ^ 

r-H cy. r-H 



CM 

o ro en 



0> vD >d- 

.-I r^ 



o CO n 



ON 00 VO 

00 
<1- 



CM 

o n CO 



o> 00 00 

to CM 



vo o in 



^ CM in 

.-I r~ 00 



cr\ r^ r^ 



-* >* in 
i-t r- 00 



r^ O o 
vo 00 



00 r^ 



in 

1^ CM 
CM 



vo 



0) 



60 
CO 
CO 
O 
Q 



CO 00 00 
in CO .-I 



o <h vo 

C3^ O CO 



00 r^ CM 

O r^ vd- 



O <J- CM 
-d- CM vO 



CO 0^ CM 

<!■ m vo 



vO vo CO 

cx) cyi r^ 

CO 



O- 00 

vo CM 



vo CM -d- 

i-H in f^ 
en 



O .-I CJN 

CM vo CO 



<(■ O vo 

r-( VO r^ 

-d- 



in 00 o 

>-( O CJ^ 

m 



00 00 vO 

CM 00 Ov 



vo CM CM 

1-1 vO 00 

si- 



r^ o in 

.— I vO CJ^ 



CM in vo 

CM in o> 

in 



in 



r^ 00 
vo CJ^ 



vo m 00 

r-l en C7> 



CM 00 

o as 

vO 



-* ~d- CM 



vO 



r~ CM 
in 



in 1^ 



<f CM O 

m Si- vd- 
<1- 



CT\ CM vo r^ O -d- 
rH CM CJ^ 00 O CO 

sd- in 



o r~. .— I 
CM r-- m 



-H O CO 
CM vO CO 



00 in CO 

CO t^ CJV 



00 00 r^ 
CO <J- cj> 



CM CJ^ <y\ 
-d- 1^ cyi 



t^ O- o 

CO t-^ o 

<f ,-1 



CO o o 
CO vO O 



CO o cyi 

C7\ CO -* 
CO 



coooco co«d-in -d-inr^ <t■r^<3^ 
«d-si-vo fo-d-oo mooeyi sd-cot3^ 
>-< -* 1-1 «* CO ,d- 



■* -* o 
vo r~ O 



VO vd- o 
<f <|- o 

in 1—1 



o r-. o 
-d- m o 



Ov vo CO 
C3^ 00 CM 



0) 

3 
P! 
•1-1 
u 
C 
o 
u 

I 



r^ <f vj- 
-d- vo vo 



m m <t 
CO CO CO 

r-4 <t 



o -d- <j^ 

C7V C3N OV 
CO 



cjv -d- 00 

00 .— I cy. 



CM 

O CO .1-1 
■--, 60 J<! 
60 60 
i W B^ 



CM 



B -I 

U CD •^^ 

•^ 60^ 

60 60 



CM 

B 

CJ CO -H 
~-^ 60^ 
60 60 
i W S-S 



CM 



B ^ 

O CO .H 
•~v, 60 J«! 
60 60 
:l W S~2 



^ CO vO 
C7\ vO G^ 



<)■ 00 O 
1^ O O 

<1- .-I 



CM 

B 

O CO -H 
--S. 60^ 
60 60 
i W B^ 



-d- O <T\ 

r^ I^ C3^ 

-d- 



CM r-l 

B ^ 

CJ CO -H 
-«- 60j<i 
60 60 

:i W s-s 



CM r-( 

B -I 

O CO -1-1 

-s> 60^ 

60 60 



1^ r^ O 
O CM -d- 



CM ,-1 

B ^ 

CJ CO .r^ 

•~-> 6OJ1J 

60 60 
=1- W B~2 



H 



•rl 
O 



O 

in 

CM 



m 
vo 

CM 

I 

Pi 



in 
00 

CM 

I 



in 
C3^ 

CM 

I 



in 
o 

CO 

I 

P4 



o 

CM 

CO 

I 



m 

vO 
CO 



o 

«M 



64 



4-1 
•H 

to 

O 

(X 
CU 

-a 

IS 

o 



60 
•H 



(U 

> 



(U 
60 

cd 

CO 

o 

Q 



CTi 



00 



in 



00 



00 



CO 



''•' 0(Nr-l|||,,| OCM .-I O r-l .-I III 



00 



00 



' I I ' I I I I I ^0^00^^-l0^l-lO^Oc<^CMOvO i i i 

0<1- CO CO ,-iON o<t- 

in <!■ <)• <!■ ^ 



in 



00 



I I OOCM OvDi-i 0000OO^O00a^l^lno^0c0<^c0ln I I I 

■>* CO ooin oin oovOr-iinr^ tNoo 

"* •* sj- m >4' ''d- CM 



m 

O^CM<tOvO inOCM rOOCM 

CO r-(0 I— IvOvO.— IOr~. 

•<]■ in sj in 



O r^ i-H O vo <tsl- vO l~^ 00 CTi O CO CM 
Ooo--ior^.-iOoo sfoo ^o 

"^ in in -* <t- 



in 

CM 


CO 


CO 

1-H 


CM CN 
CN O 


(N 


in o 

.-1 o 

in 


CO 


in 


o 
o 
m 


I— { 


CM 

1—1 


CO 

si- 


00 


1—1 


in 


CM 

a\ 


vOO 

r-IO 

u-i 


a\ 
00 


1—1 


o 
a^ 


CJS 

00 


CO ^ 
vO 


m 

1—1 


CM 


o 


CT\ 

1— 1 


o> o 

CO o 

in 




OS 00 


CM 
00 


1— ( 


00 


as 


1—1 


o 
o 
m 


1—1 


CM 
CM 


sj- 
m 
<t 


CO 

a\ 


or-- 
eg o 


00 

00 


in 

1—1 


m 


r~- 

OS 


CO 00 
m 

St 


00 
eg 


O 

m 


CO 
CO 


m 


CM o 

in r^ 

•<t 


O 


as a\ 

CM \0 
St 


00 


r— 1 


m 
si- 


a\ 


>— 1 
CO 


00 

a\ 

CO 


a\ 


00 
CN 


in 

1-1 
m 


OS 


CMO 
CM O 

m 


r^ 

a\ 


ON 


St 


o 
o 

1—1 


CM r^ 
--I m 

St 


in 
00 



r^ VD vO 
00 CJN CO 

St 



<N CO St 

in CN C3S 

St 



Ov O 1— I 

CO o c:s 
in 



oo o vO 

1— I r^ OS 

St 



vo CO r^ 
CO in OS 

St 



O r~. r^ 

CO 00 CTV 
St 



COvO CO 
CM vO CJs 

in 



O r-H r^ 

St CM ON 
St 



vo r-» O 

rH OS CJS 
St 



3 

c 

4-1 
C 
O 
O 

I 
I 



St 
CJS 


VO 
1-1 
St 


VO 


VO 

a\ 


vO 
OS 
St 


St 

CJS 


eg 

St 


vO 

o 
in 


C3S 

CJS 


00 o 

eg VO 

in 


OS 

CJS 


m in 

St 1-1 
St 


CTN 

ON 


VO 
St 


1-4 00 

in OS 

St 


cor~ 
<tst 

St 


VO 

CJS 


00 eg 

St St 
St 


CJS 


eg o 

CO t^ 
St 


CJS 

OS 


O 
O 


o 
o 
in 


in 

VO 


00 

OS 


1—1 

St 


a\ 

00 


OS 
St 


CM 
St 


00 
ON 


St CJS 

m CO 

St 


VO 

OS 


00 o 

m 1-1 

in 


o 
o 

1—1 


in 
m 


>d- CJS 

CO CJS 
St 


00 1-1 
in o 

St 


00 

OS 


vo r^ 
r^ CO 

St 


00 
CJS 


00 r-. 

CO 1-1 

m 


00 

CJS 


T-l 


00 

CJS 
CO 


in 

vO 


St 

l-l 

1—1 


O 
O 

m 


1^ 
00 


00 
00 


CO 

m 


CJS 
CJS 


vo m 
00 o 

St 


o 
o 

1—1 


o r^ 
00 CO 

St 


o 
o 

1-H 


o 

CJS 


r-t O 

CM O 

St rH 


CO 00 
CJSvO 

St 


CJS 
CJS 


CM St 

00 St 

St 


OS 

OS 


St ^ 

r-. St 
m 


OS 
OS 



CM 



6 
o 



ICN 



CM 



CO T^ O CO •^^ 

■-^ 60^ ^. 60,^ 

60 60 60 60 

i W 6^ ZJ. W s~2 



e -I 

O CO -H 
■^60^ 
60 60 
i W 8-2 



6 

O CO -H 
-^ 60J«J 
60 60 
i W S-2 



CN 

B 
o 



CO -H 
- 60^ 
60 60 

i w s-e 



eg 

e 



CO -l-l 
- 60J<! 
60 60 
i W S~2 



eg r-i CM 

6 -I S 

t) CD T-l CJ 

-~~ 60 J<! ■-- 
60 60 



eg 



CO .r^ 

60^ 
60 60 
=L W S^ 



e -• 

CJ CO T^ 

■^ 60 Ji! 
60 60 
=i- W 5~S 



-§ 



m 

VD 

eg 
I 



in 

00 

eg 
I 



m 
o 

CO 

I 

Z 



o 

CM 

CO 



m 

VO 
CO 

I 



m 

CJS 
CO 



o 

St 
St 

I 



VO 
OS 



O 

VO 

I 



65 



Table 8. Effectiveness of 3 series of petroleum oils against citrus 
red mite eggs^ 





Slope of 


LD50 


, |ig/cm 


2 


LD95, 


M-g/cm"^ 




Oil 


regression 
line 


















Dose 


95% 


CL 


Dose 


95% 


CL 


N-250 


2.438 


138.0 


• • ~ 




1,950.0 


« • 




• • 


N-265 


2.528 


77.5 


• • ™ 


« • 


346.8 


• • 


- 


• • 


N-285 


3.338 


40.9 


21.6 - 


57.4 


127.3 


83.8 


- 


457.9 


N-305 


2.775 


10.3 


6.2 - 


13.4 


40.3 


32.4 


_ 


60.1 


N-320 


3.584 


7.4 


0.2 - 


10.9 


21.2 


16.2 


_ 


50.1 


N-365 


2.574 


5.6 


2.4 - 


8.0 


24.5 


18.8 


- 


42.7 


N-395 


2.557 


5.8 


4.0 - 


7.4 


25.6 


21.8 


- 


32.3 


N-440 


1.386 


2.1 


0.03- 


5.2 


32.2 


24.0 


- 


63.9 


R-250 


3.565 


126.1 


• • "■ 


• • 


364.8 


• • 


_ 


• • 


R-265 


2.457 


45.3 


• • ~ 


• • 


211.4 


• • 


_ 


• • 


R-285 


5.233 


14.4 


11.1 - 


17.8 


28.8 


21.8 


_ 


53.7 


R-295 


3.610 


9.9 


3,2 - 


14.3 


28.3 


19.0 


- 


137.7 


R-305 


2.320 


5.4 


2.1 - 


8.5 


27.6 


16.7 


_ 


88.0 


R-320 


3.104 


4.7 


2.9 - 


6.0 


15.9 


12.7 


- 


23.9 


R-365 


1.693 


2.3 


0.5 - 


4.1 


21.5 


14.9 


- 


47.6 


P-250 


2.806 


167.9 


• • ~ 


• • 


647.3 


• • 


_ 


• • 


P-265 


2.198 


58.4 


• • ~ 


, , 


327.2 


• • 


_ 


• • 


P-285 


4.631 


29.2 


22.2 - 


35.7 


66.2 


54.5 


_ 


93.3 


P-305 


2.080 


4.7 


3.1 - 


6.3 


28.8 


20.3 


_ 


48.4 


P-320 


1.784 


2.6 


1.0 - 


4.1 


21.8 


14.4 


_ 


51.2 


P-365 


1.202 


0.6 


0.1 - 


1.4 


14.9 


9.9 


. 


29.9 


P-435 


1.061 


0.7 


0.1 - 


2.0 


25.7 


18.4 


_ 


41.8 


P-520 


1.334 


3.9 


1.3 - 


6.5 


66.1 


44.9 


- 


147.4 


P-96 


1.531 


1.6 


0.5 - 


2.8 


18.6 


12.1 


. 


38.8 


R-60 


2.778 


5.6 


4.2 - 


7.2 


22.1 


16.2 


- 


34.8 



'Values for slopes of dosage-mortality regression lines and 95% confi- 
dence limits (CL) for lethal doses (LD) for 50% and 95% kill were ob- 
tained by probit analysis. Confidence limits were not calculated for 
the oils exhibiting very low toxicity. 



66 

The dosage-mortality relationships for the various fractions in 
the 3 series are shown by the probit regression lines in Figure 10. 
These regression lines show a direct relationship between efficiency 
and weight of the oil, up to a point. The trend reverses with the 
heavier fractions in each series. The relationship is shown more 
vividly in Figures 11, 12, and 13, in which LDg^ values are plotted 
against molecular weight, viscosity, and 50% distillation point, re- 
spectively. The LD95 values for the 2 commercial oils, P-96 and R-60, 
are plotted for comparison. These wide-boiling oils were slightly more 
efficient than the narrow-distilling fractions of corresponding proper- 
ty values in their respective series. The reformed oils appeared rela- 
tively more efficient than the paraffinic or naphthenic types. Only 
with respect to distillation temperature did the naphthenic base frac- 
tions show superiority to those of paraffinic base; this occurred in 
the range of 660 to 700 F. The 3 series of oil were most efficient at 
the following physical property values: 

1) Molecular weight— paraffinic, 365; reformed, 320; and 
naphthenic, 320. 

2) Viscosity, SSU at 100 F--paraf f inic , 99; reformed, 66; • 
and naphthenic, 80. 

3) Fifty per cent distillation point--paraf f inic , 752 F; 
reformed, 716 F; and naphthenic, 689 F. 

Beyond this point of maximum efficiency for each of the series, 
the trend was toward decreasing efficiency with increase in heaviness 
of the oil. 

At a deposit of 30 ^ig/cm^, selected as the maximum deposit for 
efficient kill, the curves of Figures 11, 12, and 13 show that the 3 
series of oils were ovicidally efficient down to the following minimum 
physical property values: 



67 



H 
H 

u 
w 

O 



PQ 



4 - 



1 1 ' I l"'l 

NAPHTHENIC 




99 
98 

95 
90 
80 
70 

50 
30 
15 



7 - 



6 - 






4 - 




7 - 



6 - 






4 - 



5 10 20 50 

OIL DEPOSIT, |ag/cm2 



100 200 



o 
o 
w 

H 



CO 

§ 

H 

M 
O 

o 

M 

h!5 



w 
u 

w 

PM 



Figure 10. Regression of per cent kill on deposit level for 3 series 
of narrow- boiling petroleum fractions tested against citrus red mite 
eggs. The number on each line indicates the average molecular 
weight of the fraction. The solid portion of each line indicates 
the range of data collected; the broken extension is extrapolation 
to the 50 or 95% kill level. 



68 



I I I I I I 1 I |M I I I I I I I 




i-J L 



I I I I I I I I I Ml I I I 



J.J I I 



ID 



o 
o 
o 



o 


o 


o 


o 


o 


o 


o 


o 


in 


<t 


n 


CM 



o 
o 



o o o 



o 



mo/SrI «^6ai 



o 




•H 


<f 




•U 


in 




o 
(d 
i-i 

M-l 


o 




i 










0) 






1—1 






o 


o 




M 


o 




4J 


m 




00 


o 




c 


CO 




•H 


•<1- 




1-1 
•1-1 

o 


o 




1 


VO 




g 


sJ- 




o 

s 


o 




c 


St 






-d- 




<4-l 




H 


o 




X 






o 


en 


o 


M 


01 


CM 




•H 
(U 




pc< 


CO 


o 


3 


ro 


o 


|— ^ 




<!■ 


U 


)-i 




Ed 


O 




►J 


M-l 






" 


O 


jg 


JJ CO 


00 




j: 00 


ro 


M 


00 00 






•i-( 0) 




^ 


13 <U 


O 


M 


4-1 


vo 


> 


i-l -1-1 


n 


<! 


cula 
ed m 


o 




<u u 


<r 




rH 


CO 




O CO 

o -u 


o 




4-1 -H 


CM 




y 


CO 




o -u 

•1-1 to 
4J C 


O 




CO -H 


O 




r-t CO 


CO 




0) 60 

^ cd 


O 




•H 1-1 


00 




•iH 


CN 




>^ O 
O 

(U CO 


o 




•r-l tH 


vO 




O U 


CM 




gure 11. Effi 
and 2 coinmer 



'J^' " 'IW^ 



69 







"r 


"-r 


1 


1 






|i 1 1 1 1 I 


1 |IIM|I 1 1 


-?— 










- 


















- 






CM 




>- 
















• 1 
1 1 




o 

o 






















■ 






<f 






■ 
















ll 


- 






to 




— 
















1 • 


— 


o 
00 

CO 




C 

o 

•H 
4J 






■D 














l[ 


- 


o 




to 




~ 


1 


o 














— 






M-l 

e 

3 
(U 
1—1 

o 




_ 


14 


1 

OS 

< 














- 


o 








J 




u 














CO 






s 


Q 


g 


















4-» 

(U 




f>4 




H 










>^ 


i 








4 


£ 


O 


K 










\l 








^ 




c 


^ 


h4 


(^ 










\^ 




' * 




•rt 




^ 


§ 


^ 










1 


- 






i-H 

•1-1 

o 




_^ 4 




• 


tf 










A 




o 










1 












l\ 


^— 


CM 






- 




1 
1 












'\l 




CM 


fe 


1 








1 
















o 


u 
to 

c 




^ 




t 












1 «• 




o 


o 








1 
1 












' 1 


^^ 


o 


1—1 




- 




1 

1 












1 \ 


- 




^ 


4^ 
o 




- 




1 

• 


• 












\ 


mm^ 


o 
t» 


t3 


CO 

•H 






















\ 




T-K 


w 




- 


















\ 


_ 






1-1 






















\ 




o 


s"^ 


to 




















' \ 


*■■ 


1—1 


M 


n 




_ 
















\ 






o 


o 




















\ 




o 


u 

CO 
M 




















1 \ 


~ 




> 


>, to 

4-1 60 




















'\\ 


- 






•H 60 
to 0) 




— 
















— 


o 

CM 

i-l 




o 

CO 4-1 

•H •!-( 




~ 
















1 » \ 


_ 






> e 




— 














■■ 


1\ ) 


— 


O 

o 

1—1 




O T) 
4J (U 

c 

o to 


















■^■' 








•H 3 


















v 








4-1 ^4 




— • 



















o 




CO 4-> 




















\^ /o\ 




CO 




r-l -H 
01 U 




- 






_ 


. 


—- 


— 


.^ 


V'"- 


— 


o 




cy in r 
gainst 


■ 


- — 


— 


■ — r: 


-- — 












— 


o 




C CO 

•r4 CO 
O 1-1 


; 




L 


1 


1 


1 




1 


1 1 1 1 1 . 


I ' '* " 

II 1 1 1 1 1 1 1 


1 






12. Effi 
lercial oi 


o 
o 
o 


c 
c 
1/ 


3 
3 

1 


o 
o 


o 
o 


o 
o 

CM 




o 
o 

r-l 


o o 


O O 
CO CM 


o 

r-l 




1-1 






















3 O 














z""' 


/sn 


'''ai 












60 
•i-l 



70 



o 
o 
o 



OS 

1 


o 




PM 


1 




o 


<1 




u 




o 


H 


A 


H 


z 


o 


Z 


M 
P4 




H 


2 


o 


3S 


Ph 


Pm 


pL, 


■^ 


W 


< 


p^ 


Pri 


Z 




o 
o 



o 
in 

00 



o 
o 

00 



o 



o 

o 



o 

ITl 



I ' ' ' ' 



J 



o 


o 


o 


o 


o 


o 


o 


o 


in 


<f 


n 


CM 



o 
o 



o o 

in <)• 



o 



O 
CM 



H 

M 
O 

z 
o 



H 
w 

M 
Q 

S^ 
O 

in 



0) 

1-1 
o 
u 

<u 

QO 



o 

I 



u 

u 

CO 



CO 

<u 

•H 

^ 

0) 
03 

<r) 

^1 • 

O to 

m 60 

M 

4J <U 

C 

•H 41 

O -U 

a ^ 

o X) 

•H (U 

■U U 
CO 

r-< CO 

r-i 3 

•H K 



CO 

•rl 
13 



o 
m 



uio/StI 



.S6 



ai 



CO 

C 
•1-1 
CO 
bO 
cfl 



C CO 
O 1-1 

•A irl 

•u o 
cd 

1-1 r-l 

(U Cd 

O 

C M 

y ° 

C cj 
(U 
•1-1 cs 

u 
•H -d 

M-l § 

Pd 

CO 

CI 

• o 
en -H 

1-1 4J 

u 

(U CO 

S 14-1 

oo 



71 



1) Molecular weight--reformed, 285; paraffinic, 304; and 
naphthenic, 313. 

2) Viscosity, SSU at 100 F--reformed, 52; paraffinic, 61; 
and naphthenic, 75. 

3) Fifty per cent distillation point--reformed, 660 F; 
naphthenic, 677 F; and paraffinic, 694 F. 

The property values for maximum efficiency and the minimum proper- 
ty values for efficient kill were slightly higher for citrus red mite 
eggs than for red scale. However, LD95 values for red scale were more 
than double those for the mite eggs, except with the 265-mol wt frac- 
tions. These lighter fractions attained 95% kill of red scale at 90 to 
100 ^ig/cm , but required over 200 [ig/cm for citrus red mite eggs. 

The 4 oils applied in Field Experiment No. 1 covered a viscosity 
range of 60 to 90 SSU. Detailed spider mite counts were made 1, 4, and 
7 weeks after application. The data presented in Table 9 show the 
relative abundance of citrus red mite and Texas citrus mite, 
Eutetranychus banks i (McGregor), at these times. All 4 oils signifi- 
cantly reduced the spider mite population throughout the 7-week period, 
except for Texas citrus mite in the seventh week. Although differences 
between oils were not significant, residual control by the heavy and 
medium oils appeared better than by the light oil. 
Discussion 

These studies were primarily concerned with the relationship of 
chemical composition and heaviness of petroleum oil to insecticidal and 
ovicidal efficiency. The main comparisons for composition were between 
the paraffinic and naphthenic series. The reformed oils were paraffinic 
fractions obtained by a special refining technique which resulted in 
products of slightly lower paraffinic hydrocarbon content than the 
paraffinic series. This was probably due to the retention in the 



72 



Table 9. Spider mite counts at 1, 4, and 7 weeks after application of spray 
oils on 6 May 1964 in Block 23 

Plot Live adult female and young mites per 100 leaves per 4- 
Treatment (4 trees) tree plot^ 

Citrus red mite Texas citrus mite 



1st 4th 7th 1st 4th 7th 

week week week week week week 

Check 1 24 260 272 284 2,656 23 

2 20 236 532 172 2,204 48 

3 24 288 456 140 3,828 36 

4 _0 J^ 228 _80 1,044 28 

Mean 17.0 a 238.0 a 492.0 a 169.0 a 2,433.0 a 35.0 b 

R-60 1 4 . 32 76 112 1,180 84 

2 4 48 136 116 500 88 

3 36 184 116 124 88 

4 92 212 100 728 76 





Mean 


2.0 


b 


52.0 b 


152.0 


b 


111. 





ab 


633.0 


b 


84.0 


a 


P-96 


1 
2 
3 
4 









4 
16 
12 

4 




36 
52 

116 
68 




80 



108 

112 






188 

340 

36 

24 




20 
52 
64 
64 






Mean 


0.0 


b 


9.0 


b 


68.0 


b 


75. 





b 


147.0 


b 


50.0 


b 


BR-1 


1 
2 


12 
4 




8 
4 




36 
44 




28 
28 






160 
168 




32 

16 






3 







32 




32 




48 






88 




12 






4 


_4 




8 




68 




124 




— 


76 




56 






Mean 


5.0 


b 


13.0 


b 


45.0 


b 


57. 





b 


123.0 


b 


29.0 


b 


BR- 2 


1 
2 
3 

4 





8 




12 

s . 

16 
8 




136 
136 
148 
176 




12 

8 

8 

100 






308 
268 
260 
120 




52 

88 

124 

124 






Mean 


2.0 


b 


11.0 


b 


149.0 


b 


32. 





b 


239.0 


b 


97.0 


a 


Total mites 


for 




























each week 




104 


1 


,292 




3,624 




1,776 




14 


,300 


1 


,180 





treatment means for a given week followed by the same letter are not sig- 
nificantly different at the 5% level according to Duncan's New Multiple 
Range Test. 



73 

refining process of certain ring compounds (e.g., naphthenic acids and 
partially saturated aromatics) which are removed in the normal acid 
treating process of refining. The 3 physical properties discussed, 
molecular weight, viscosity, and distillation temperatures, are all 
measures of oil heaviness. 

The most striking features of the results as depicted in Figures 
7 to 9 and 11 to 13 are: the relative efficiency of the 3 series of 
oil fractions; the abrupt change from increasing efficiency with in- 
crease in oil heaviness to a more gradual rate of increase--especially 
with citrus red mite eggs; the trend of decreasing efficiency beyond a 
point of maximum efficiency- -especially with Florida red scale; and 
the difference in the minimum effective dosage for the 2 pest species. 

The relative efficiency of the 3 series of oils tested, in de- 
creasing order, was reformed, paraffinic, and naphthenic. These re- 
sults are in general agreement with the findings of other workers (9, 
42, 43, 44, 47, 48, 49). Chapman et al • (9) summarized years of exten- 
sive research and cited other workers in correlating basic structural 
composition of petroleum oils to insecticidal efficiency. Paraffin 
content was found to be the key variable among saturated compositions 
and a direct relationship between efficiency and the proportion of car- 
bon atoms present in the form of chains was established. Riehl and 
LaDue (47) found paraffinic oils superior to naphthenic oils against 
adult female California red scale and citrus red mite eggs in labora- 
tory studies similar to those reported herein. Riehl and Carmen (48) 
and Riehl and Jeppson (49) reported the same relationship under field 
conditions in California. Thompson (84) reported no difference between 
paraffinic and naphthenic oils in scale control on citrus in Florida at 



/ 74 

1.3 to 1.4% oil concentration, but at 1.07o there was a slight trend in 
favor of the paraffinic type. 

While the results obtained in the present work support the above 
conclusions, the correlation between paraffin content and efficiency 
was not as pronounced. The reformed series, which is indicated by the 
data in Table 3 as being intermediate in paraffin content, appeared 
more efficient, up to 340 mol wt and 85 viscosity, than either of the 
other 2 series. With respect to 50% distillation temperature, the 
naphthenic series tended to be more efficient against both pest species 
than the paraffinic series, at least in the low portion of the efficient 
range of distillation temperature. 

The change in increase in efficiency with increase in oil heavi- 
ness was more abrupt where heaviness was measured by molecular weight 
(Figures 7 and 11) and viscosity (Figures 8 and 12) than where measured 
by distillation temperature (Figures 9 and 13). The curves showing the 
relationship of LD95 values to molecular weight and viscosity are strik- 
ingly similar to those presented by Riehl and LaDue (47) for California 
red scale and citrus red mite. The pattern of the curves was quite 
similar in both instances. The main differences were that generally 
lower LD95 v^l^es were obtained in the present work and the importance 
of chemical composition was not as apparent as was shown by the above 
authors. Riehl and Carmen (48) concluded that insecticidal efficiency 
for California red scale increased with increase in molecular weight up 
to 360, and Riehl and Jeppson (49) reported a critical value of 340 mol 
wt for citrus red mite control in the field. 

Pearce and Chapman (44) obtained maximum efficiency at 320 mol wt 
for European red mite eggs, cottony peach scale nymphs, and oriental 



75 



fruit moth eggs. The minimum molecular weight values for efficient 
kill established in the present work were considerably lower than the 
above values, but the points for maximum efficiency obtained here were 
quite similar. 

Beyond a point of maximum efficiency for each of the 3 series 
studied, the trend was toward decreasing efficiency with increase in 
oil heaviness. This reversal was much more drastic with Florida red 
scale than with citrus red mite eggs. Riehl and LaDue (47) observed 
the same phenomenon with California red scale but not with citrus red 
mite eggs. They reasoned that the spreading characteristics of the 
larger hydrocarbon molecules was the limiting factor and were able to 
show some proof of this by diluting the heavier fractions with a non- 
toxic amount of kerosene to reduce the viscosity of the oils. Pearce 
and Chapman (44) obtained similar results with oriental fruit moth eggs 
and greatly increased the efficiency of a 479-mol wt isoparaffin by 
diluting with deodorized kerosene. Thompson (84) reported no differ- 
ence in scale control on Florida citrus with oils in the viscosity 
range of 72 to 100 SSU. The screening data for the commercial oils 
presented in Table 6 tended to bear this out. Although differences 
occurred at the low deposit level, these were not correlated with 
viscosity, which ranged from 57 to 112 SSU. At the high deposit level, 
all the oils were effective. The field data for spider mites presented 
in Tables 9 and 10 failed to show significant correlation of control to 
viscosity in the range of 60 to 90 SSU. 

Although the minimum LD95 values obtained for Florida red scale 
were 2 to 3 times as great as those for citrus red mite eggs, it is 
interesting to note that the very light fractions in each series 



76 

attained 95% kill of red scale at a much lower deposit level than for 
citrus red mite eggs. Pearce and Chapman (44) observed this same dif- 
ference between cottony peach scale nymphs and eggs of both European 
red mite and oriental fruit moth. They suggested that this difference 
may be due to the differences between the respiratory systems of the 
active insect and the mite egg. 

Correlations between efficiency and 50% distillation temperature 
for both test species are depicted in Figures 9 and 13. Very little 
difference was shown between the paraffinic and naphthenic types. 
Chapman et al . (9) stated that distillation range is the single most 
useful physical property for specifying a spray oil since this is most 
directly related to the volatility of the material. The results ob- 
tained here suggest that naphthenic oils may be equally as efficient as 
paraffinic oils if compared on the basis of distillation temperature 
rather than viscosity or molecular weight. 

Comparison of the 3 series of oils tested in these laboratory 
studies at the LDg^ values of 30 and 70 |ig/cm^ for citrus red mite eggs 
and Florida red scale, respectively, has much practical significance. 
The recommended rates of oil applied for spider mites and scale insects 
on Florida citrus are 0.7% and 1.3%, respectively. With standard field 

application procedures, sprays containing these oil concentrations de- 

2 
posit in the neighborhood of 30 and 70 |ag/cm , respectively. Therefore, 

the correlations made between these maximum efficient deposits and the 

physical property values may indicate that the use of oils lighter than 

those presently used on Florida citrus is feasible, in which case some 

of the phytotoxicity problems discussed in the following section may be 

alleviated. However, it is often difficult to obtain uniform 



distribution of oil deposits over the entire citrus tree. In such 
cases, the inhibition of crawler settling by the residual oil film be- 
comes the important aspect of scale control. The increased dissipation 
rate of the lighter, more volatile oils, and consequent reduction in 
residual effectiveness, may be the limiting factor in the use of oils 
lighter than the 60 to 70 viscosity range. 

Relation of Composition, Heaviness, and 
Refinement of Oil to Phytotoxicity 

Respiration and transpiration 

Results. --Determinations of the respiratory rates of treated and 
untreated leaves of 'Pineapple' seedlings were made 1, 3, 7, and 14 
days after treatment with 305- and 365-mol wt fractions of paraffinic 
and naphthenic oils. The mean of 6 determinations for each oil are 
presented in Table 10. Analysis of variance of the data detected no 
significant difference between treatments at the 5% level. In a 
follow-up experiment, P-365, at 154 ng/cm^, effected reduction in O2 
uptake of 4.3%, 11.8%. and 16.0% on the first, third, and seventh days 
after treatment, respectively (Table 11). The reduction on the third 
and seventh days was highly significant. 

The relationship of oil heaviness and composition to effect on the 
transpiration rate of 'Pineapple' seedlings is shown by the data in 
Table 12 and by Figures 14 and 15. The transpiration rate for the 
check is given as mean water loss in mg/cm^ leaf surface per day; the 
rates for the treated groups of plants are presented as per cent of the 
check. Analysis of variance was run on the data in mg/cm2 per day, and 
the means were converted to per cent of the check for presentation. 



78 



Table 10. Respiratory rates of oil-sprayed 'Pineapple' 
seedlings expressed as per cent of the check, 
Each value is the mean of 6 determinations. 
Oils were applied at 70 to 80 |j.g/cm2 







Days after 


treatment 




Oil 


1 


3 


7 


14 


P-305 


105.1 


100.5 


98.6 


87.4 


P-365 


112.4 


94.4 


88.2 


97.6 


N-305 


92.7 


98.8 


96.2 


102.4 


N-365 


85.2 


101.8 


96.5 


103.4 



79 



T) -H 




(U 




4J 0) 




S-^ 




M 4J 


^ 


4-1 O- 


bO 


3 


•H 


4-1 


J2 


C cs 




0) O 


CO 


u 


CO 


CO to 
.1-, cS 


s 


TD 


4J 


n) TS 


•H 


0) 


CO 


M-l M 


O 


O 3 


a 


M 


(U 


a to 


-o 


o a> 




•H a 


r-l 


4-» 


•H 


rt « 


o 


u to 




•i-l 60 


<u 


CX C 


^ 


CO -H 


H 


(U .-H 




U X) 




t) 


• 


C <U 


T3 


O to 


O 




•H 


1-1 - 


)H 


•I-l 0) 


<u 


O r-l 


a 


a 




o P^ 


I-l 


•M CO 


3 


Pi (U 


O 


•H C 


s: 


M-l .r-l 


1 


ly PM 


CM 


CO - 




CO 14-1 


CO 


& o 


C 




•r-l 


4J U 




S <U 


(U 


> 


u 


.-H CO 


CO 


(U 


IH 


a ^ 


U 


1 


3 ^ 


u-i 73 


CD CSJ 


vO 0) 


B 


CO J-i 


4-1 O 


CO 


CO ^ 


M-l OJ 


<U bO 


O M 


.-1 ZL 



4J 
■U C 

O 3 

(U 

IH T3 
^ C 
W « 



H 



B • 
y >* 

00 .-I 



C 

e 

4-1 

CO 
lU 
U 

u 

u 
<u 

4-J 
t4-l 
CO 

CO 

CO 
Q 



T3 

<u 

4J 

to 

H 



(U 

4J 

CO 
(U 

4J 
C 



0) 
4J 
CO 
U 
I-l 

H 



0) 

4-1 

CO 
(U 
U 

c 



-a 

(U 

u 

CO 

<u 

M 



(U 
4-1 
CO 

<u 
u 

4J 

c 



o 


u-i 


C^J 


VO 


VO 


o 


CM 


.— 1 


vO 

CO 

1-1 


CO 

r-l 


1-4 

1-1 


CO 

1-1 


CO 

1-1 


CO 

1—1 



■a 



o 



CO 


lO 


o 


o 


vO 


1-1 


>* 


vO 

I-l 


o 

I-l 


o 
1^ 

I— 1 


m 

1—1 


1-1 


o 

vO 
I-l 


CO 
vO 

I— 1 



0^ 


o 


m 


CJV 


r-» 


•* 


CM 


VO 
CO 

1-4 


VO 

1-4 

i-H 


Cvl 

CO 


in 

CO 

r-l 


CN 
CO 

1—1 


CM 

r-l 


O 
CO 

I-l 






00 



CO 



o 

U-I 



00 



o 






lO 



as 



CO 



O 

LO 



t^ 
-* 



CO 


in 


■<r 


-* 


CO 


a\ 


vO 


1—1 

CO 

I-l 


vO 
CO 
1—1 


00 

CO 

1—1 


•<)■ 

1-1 


in 

CN 

rH 


o 
<!■ 

1-1 


vO 
CO 

1-1 



CO 



o 


CO 


vO 


^ 


vO 


o 


00 


1-4 
i-H 


CO 

vO 

1— 1 


CO 
CO 

i-H 


CM 

<!■ 

1—1 


in 

CO 

1—1 


r-l 

1-1 


CM 

1—1 



<u 






o 

•I-l 
m 

•H 

a 

60 
•H 
CO 



C 

C3 '1-4 
Hi u 

u u 

3 

u Ta 

Ph I-l 



> 
<u 



0) 

J2 



4-1 

to 

<u 
u 

§ 

u 

•1-1 

U-I 
•rl 

c 

60 



CO 
01 
4J 
CO 

u 

•H 

•a 

B 



CO 

•I-l 

M 

(U 
4J 
CO 

CO 



3 
o 

Q 
■X 
* 



80 



•H 




•o 




(U 




e 




„ 




^ 




o 




1—1 




>w 




o 




C! 




O 




tA 




•u 




cd 




u 




■u 


CO 


a 


r-l 


(U 


•i-l 


u 


O 


d 




o 


CJ 


u 


•1-1 




c 


R^ 


<u 


in 


4: 


• 


•u 


r-l 


4S 




ta. 


^ 


CO 


w 


ti 


•H 




S 


"^ 


-o 


§ 


(U 




>. 





Cd 


•H 


u 


C 


P- 


•H 


co 


<4-l 




IW 


03 


CO 


M 


M 


c 


CO 


•H 


0. 


i-l 




Tl 


4-1 


0) 





0) 




CO 


CO 







M 





<u 


•H 


I— 1 


4-1 


tx 


C) 


Ch 


CO 


cfl 


u 


(U 


IW 


a 




•r-l 


4-1 


Ph 


^ 




60 




•H 


iw 


tu 


o 


15 


<u 


M 


4-1 


CO 


CO 


1-1 


U 


3 




c.; 


c 


0) 


o 


i-H 


•f-i 


n 


4J 


fi 


CO 




M 


x: 


•rH 


W) 


ex 


•1-4 


to 


XI 


§ 


"2 


M 


C 


H 


CO 



c^^ 






CO 
O 

<u 
o 

M-l 
O 

4J 
C 
CU 

o 
u 

CO 
CO 



t-l 

P4 

CO 



14-1 
o 



CO 
U 
•H 
Ph 
CO 

C 
CO 

H 



•H 
O 

o 

•1-1 

c 

(U 

4: 

4-1 

x: 
& 



en 



o 

CM 

n 
I 



in 

(30 
<N 

I 

2: 



in 

vO 

I 

PM 



O 

CM 

ro 

I 

PM 



CX3 

CM 

I 

Pm 



CO 

CO ^ 

CO OCM 

o 0) e 

U 00 

(u B g 

CO ^ fi 

^ IH -1-1 



6 4-1 

O G 

M <u 

4J 

CO CO 

>> Q) 

CO (^ 

Q 4J 



CO CO CO CO 
O vo in ro 



CM rH CM <t 

cyi o ty> cj\ 



CO CO CO CO 

o fo in CO 



t-i CO m r^ 
CJv (X) ■-* <3^ 



CO CO CO CO 
CO m r^ 1-1 



vo <t --I <^ 

CX) O 1-4 O 



CO CO cfl CO 

en 00 CO 



in vo cN in 

00 1-1 o o 



CO CO cfl CO 

vo in in r-i 



CJ^ r^ en O 
00 e3> o O 



cd CO CO CO 

00 CM en o 

in <J^ o 00 

I— I o 1— I cyi 



000 

^ ja ja -o 



<)■ r^ <f in 



o CJ CJ 43 



in in vo vo 



vo en m -* 
r^ in <!■ vt 



O O 13 
O XI XI CJ 



r^ 1— I vD 1-1 



t-^ O O O 

^ <t- <t m 



CJ 
XI XI ,i2 CO 

~d- o> T— I vo 



vo 00 in en 
r^ vD vo r^ 



000 

CO X3 XI X 
O (N in CM 



00 O 1-1 vo 

CJ^ vo in in 



X X 

cfl X X CO 

<f 00 00 vO 



1-1 1-1 en 00 

CT\ vD vo r^ 



CO o O 73 
vx r^ CM O 



vD <!■ O ^ 

in in in f^ 



O XI 

u X o X 



C3> <^ 1-1 en 



o in o r-i 

<J\ If) <} ITi 



•a 
CJ o o 

CO X XI X 

«* <t vO CM 



vj- CM 1-1 O 

in vD in r^ 



■5 " 

CO X X X 

00 in o r~ 



i-( en 1— I o^ 

00 v£) v£> vO 



X 
CO CO CO X 

1-1 o 00 1-1 



1-1 en 00 r- 
00 r^ vx r~ 



a CJ o 

X X X X 

o o in en 



00 vO 00 1-1 
r^ 00 0^ 00 



O O X) 
CO XI X CJ 

o vo 1-1 in 



00 CJN CM 1— I 

>x in in r^ 



cTi en -^ 1-1 
r^ ^ m vo 



CJ 

X X X X 



r^ m vD o 



X> X CJ 
CO CO CO ^ 

o vD -* in 



<!■ en O vl- 
r-. r^ t^ r^ 



r~- CM m CT^ 

00 00 r^ r-- 



13 CJ x) "O 
O vo in ^ 



t^ en CM »3- 
^ in in in 



X) ta 
CJ u u 

XI X X X 
r-- in t^ CM 



u 

T3 o 
<l-cneMco (U4-ii-i(Nen<j- 

1— I i-H 1— I >. o 

I I I I CO o 

u 

0.00 
CO CM 



O 00 O CM 
1^ \0 r^ 1^ 



U X X X 
X CO CO CO 

vO »d- vO 1-1 



o in cj\ in 
00 00 00 00 



X) CJ 13 13 

0x00 



in vD vi" ■— I 



vO CM vO 1-1 
in vO vO vD 









XI 








XJ 


X 


CO 


CJ 


CJ 


XI 


XJ 


X3 
CJ 


X) 





CM 


en <)■ 


1—1 


0^ 


1-1 


I^ 


■4- 


en 


e3> 


m 


<t CM 


in 


VO 


00 
v£> 


en 


en <)• 
en en 


CM 

in 


vO 


en 


■J- 


00 


en 


in 


m 


O- m 


1-4 

vO 


1^ 

m 



u 

X o CJ 

X CO ^ J2 

o 00 vi" in 



C3N 00 vo r^ 
r^ r^ p>. r^ 



CO cfl 


cfl 


CO 




cfl Cfl 


cfl 


CO 


cfl 


CO 


Cfl CO 


CO 


CO 


CO 


CO 


CO CO 


CO 


CO 


00 CM 





1-1 




en en 


CM 


en 


00 


vO 


o- 


Cvl 


m 


<f- 


r-v 


CM 00 


r-4 


c^ 


1— ( 


1—1 


1-1 


vi- 
vo 


in <}• 
t-H eg 




CM 


vo 

1—1 


in 

1—1 


<f 00 

Cvl 


00 


m 

CM 


vO 
CM 


in 

1-H 


CM CM 
CM CM 


CM 
CM 


CM 
CM 



































in vo iv. t» 



CJ^ O 1— I CM 



en <j- in vo 



81 



XI 

<u 

3 
C 

•H 
J-l 

CI 

o 
o 

I 



-§ 





















>N CU 








j3 -a .0 XI 


X3 


XI cj -a XI 


XI XJ 


13 -O T) CJ 


X3 60 






in 












c 






^ 
n 


CN rH VO CN 


<h <h 


VO CM 00 


vD 00 CO 


1— 1 i-H 1— 4 vO 


•0 CO 


ca 




cTn vO vO 


ON cx) (» 00 


CO CM in 


vD ON (N CJN 


CO ON T-l 


0) p:; 
IS M-l 


M 




2 


r^ in in vo 


vo in vo in 


vo r^ \o r^ 


r^ s^ vo '^ 


r~ «d- m in 


0) 


o 
















1—1 1—1 


cu 
















1-1 0-4-1 


JZ 
















Ot4 C 


o 


CO 

i-H 














14-1 4J 0) 
1-1 


m 


•r-l 
















(US 


o 


o 




•£ =J - -2 


^ ^ ^ ^ 





xa 


X> X3 X) 


i-i S M 








CO ^ CO CO 


CO CO CO CO 


CO CJ XI X3 


X) ^ CO CO 


CO CO CO CO 


CO (U 


■u 


o 















& a, 




•1-1 

c 




(X) vO 


CO vo vO 


r^ r^ 


t^ t^ in CO 


r^ CN CO in 


x: cu 


o 


m vt r^ 


CN vj- <i- <i- 


(N C3N r-l fO 


1-1 <f 


vo r^ r^ vo 


!a 

•r-l 4-1 




4:; 


!z; 


cx) c» <x) 


00 C30 


00 r^ 00 00 


1-1 cjN 


CJN ON 


x; CO 


a 


4-t 

a. 

CO 




j—i 


T-^ ,-1 




1-4 1—1 1— 1 


i-H 1-1 


t- -0 

fl <u 

>^S 4J 


to 














CO k 
X> C (U 
















3 > 


en 






CO CO cO CO 


CO CO CO CO 


XI JO 
CO CO CO cO 


CO CO CO CO 


CO CO CO CO 


<u 


■U 




in 

C30 
CM 


ft-) r^ ^ 


vo 00 in CM 


C7N r^ vo 


in CO in 


CJN CJN CN <|- 


> CJ 
•1-1 u 


i-( 




in in in 


in cv) <f vo 


in <t 


-4- <3N CN ON 


• > • • 

r^ CN CO CJN 


60 CO 
60 C 


n. 




2 


(Tvl i-l CJ> CTi 


CJN 1— 1 CO CN 


C3N ON CM 


in <t CN 


CN 1-1 CM 


CO C CO 








r— 1 r-H 


r-4 I— 1 ,— 1 


1—1 i-H 


i-H 1-4 1— 1 i-H 


1— 1 1-4 r-4 r-4 


•r-l lU 


(U 














MX) B 














1-1 

14-1 •" 
















UCM 






T3 





•0 




■a 


CO B 


CO 






XI X3 XI 


X3 XI 


cj XI 


XI XI 


X) T) U 


t— 1 

•H 

o 




n 
1 


I— 1 ON \o r^ 


CJN CO 


vO t-l <f CX) 


i-H VO 1^ 


1-4 .-1 cj\ 00 


(Ui-H 60 

B <u B 


ro CN vo 


CO 00 .-1 vO 


CTN <j- 00 m 


CO CJN C3N (JN 


1—1 ON vO 


> 

4J <U C 


o 




PM 


r^ r^ vo vo 


vo vo 00 in 


in r^ ^ t^ 


r^ vo in 


r^ vt vD in 


Ci-I -H 


CO 
>— 1 

•H 
















0) 

Bs^ CO 


4-1 

CO 














4-1 in CO 
CO 
(U (U 1-1 








T) 





T) T3 X) CJ 


S-i JZ 


>-i 








XI T) X2 XI 


0000 


XI 


X3 X3 XI 


cj XI 


0) 
4-1 4-1 


o 

•rl 


C 

•H 


CN 

1 


CO in vo 
• ■ • • 


00 CO a\ 


CO 00 <!• 00 


00 CN <J- 


00 r>. [^ 


■-< 1-1 <f 


in r^ -d- 


vO 00 t-l 


CO 0\ <t (JN 


• • • • 

CO in in CO 


• CO CO 
CO S 


4-1 

cd 


M-l 
14-1 
CO 


PM 


vo in vo ^ 


vO LO vO vO 


vo ^ r^ 


r^ vo r^ ^ 


r^ in r^ vo 














c >. 


CO 


CO 

PL4 















•1-1 cu 1—4 
4J ^1 -1-1 
CO CU CO 
OIWXI 






XI XI 


u XI 


XI 


a X3 


•H 14-4 
1-1 .i-l c 

ax) 

(U 

M >m3 


}>4 

H 




in 


CO CO CO CO 


CO CO CO CO 


XI XI X3 to 


XI XI X3 CO 


XI XI XI CO 






c» 


in r^ CO 


IM CO ON CT\ 


vO <)■ CO CM 


CT\ CM in 


r^ C3N r-~ r^ 


<j- .-1 r^ sj- 


1^ CM r-4 


CJN vO 


vo <t r^ 


• • • • 

00 CJN 00 r^ 


1-1 3 
in 4-1 (.1 
c 






P4 


CJN C3N 00 00 


00 ON CO 


r^ 00 00 (3N 


C3N 00 00 


CJN 1^ 00 00 










1—1 1-4 




i-H 




4-1 CO a) 
















M 
















•H CU 
















con-i 5 
















CtH 
















CO c (U 
















cu 60 




CO 












B-i S 




CO ^ 












CO CO 




CD OCvJ 

<u B 

~-^ 


X3 XI 
CO CO CO CO 




CO CO CO ^ 


CO CO CO cO 


X3 X3 

Xi XI to CO 


XI 

XI CO ^ CO 


(U •rH ,^-\ 
>J 4J k . 
CO CO C 

m ^ ^ S 




U 60 

(UBS 
4-1 

(0 i^ e 

S "+4 -H 


.-( -;t CN CJN 


cjN CN in CM 


00 in in r^ 


CO CJN <3N <)- 


ro 1— 1 vO in 


(U -1-1 
1-1 (U 4-1 4-1 


in CJN (» CM 


00 00 >-l C3N 


CO in vo 


1— 1 (3N vD 


r — 00 r^ r^ 


XI ^-1 CO 
CO CO 4-1 




n CN .-1 CN 


1— 1 r-l 1-H CM 


1-4 1—1 1—1 i-H 


CM 1—1 1—4 1—1 


r-4 1— 1 r-^ r-4 


■u CO C 
















k (U (U 
















0) cu CO CO 
















x; J-i i>N<u 




• • 




i ' 




; ■ ■, ; ■ 




W 4-li-H M 

<u CO a- 
S.-I g 




B -w 




• 1 


- ■ 








c 












<uv_^o 




1-1 (1) 












CO E 4-1 


c 


CO CO 


r-~ 00 (3s 


1-1 in vo CN 


CO <f in CO 


<J- 1-1 CN 


r~^ 00 CJN 


OJ CO 

M CO -^ 

3 4-10 




I— 1 i-H 1— ( <N 


CN CN CM CO 


CO CO CO in 


in vo vo vo 


vO vO vo r^ 




K^ <U 












60 <U CO (U 




CO U 












•Hjr (ux: 


( 


3 4J 


1 












fa -i-i H 
CO 



82 



} 



u 

IS 



o 
B 



J-l 4-1 



o o 

B B 



mom 
00 csl ^ 
<N en en 

o < a 



o 




- 2 ^ 



H 



Ed 
Pi 
H 

w 

H 



CO 
Q 



0) 
U 

4J o 

to T-l 



60 



O CO 

(U <U 

4-1 4J 

CO CO 

u u 

•H 

o c 



cd 09 

M .-I 

CO CO 

us « 

CO 

c 
o 



to 

c 
o 
•t-l 
u 
O to 
CO 0) 



u 

c 

(U 

a 



o u 

•1-1 <U 
C -u 

•1-1 4-1 
U-i eO 

to 0) 

to -H 

>. o 
Xi o 

•H 

§;5 



(U to 

a C)0 



Si X) 
bO (U 

•1-1 (U 



4-1 (U 
O 60 

c 

CO 

o 



u 

y-i 



.-I u 

a. a 

• ax; 

<r to u 

I— I OJ 

c 

01 •H 



xoaHD 10 iNa3 Had sv aiva NOiivaidSNvai 



3 
60 



h 



a 
o 

M 



83 



i- / 



4^ 




_ <)■ 



C3^ 



r^ 
^ 



CM 



O 






0-) 



CM 



CM 



o 



00 



VO 



i 



°P 



H 
12 



^ 



OS 

w 

H 
CO 

<! 
Q 



0) 

U 

•T3 C 

0) tfl 

4-1 U 

01 <+-) 

4J C 
60 

O CO 

0) (U 
JJ 4J 

^ o 

•r-i 

c -a 
o c 



tfl en 

^1 --I 

•H o 

03 6 

c >< 

cfl en 

J-t T3 

<u 

^ cfl 

■u ^ 

c 
o 



en 

a 

O 
o 



cfl <U 

14-1 4J 

o u 

•r-l 0) 
C 4-1 

x; cfl 

4-1 

cfl T-l 
C 4J 

>. o 

•H 
C CO 

cd r-4 

0) 

•> U 

§c 

1-1 -H 

Q) cn 

E 60 

C 

•> -w 

4J 1-1 

60 (U 
•i-l (U 
1—1 CO 

M-l 0) 
O 60 



M-( - 



cfl 

O U 
0) 



)1D3H3 JO INSD HSd SV aiVH NOIIVaidSWHI 



• ax: 
in cfl 4-1 

I— ( 0) 

c e 

<U -r-l O 
3-14-1 

60 
•H 



84 

The response of the plants to the various treatments is readily 
apparent from the graphs in Figures 14 and 15. The 320-mol-wt 
paraffinic oil and all 3 naphthenic oils effected significant reduc- 
tion in transpiration the first day after treatment. Further reduction 
occurred with all 6 oils on the second and third days, after which some 
recovery was evident. A strong recovery period began after the seventh 
day for all the oil-treated plants and none were significantly differ- 
ent from the check on the ninth day. After this time, the P-320, P-365, 
and N-365 fractions significantly depressed transpiration throughout 
the remainder of the 70-day period of measurement with only a few days 
excepted. The transpiration rates of the plants treated with the P-285, 
N-285, and N-320 fractions were not significantly different from that 
of the check after the ninth day except on occasional days. The plants 
treated with the N-285 oil transpired at a level significantly higher 
than the check on several days. In Figures 14 and 15, the shaded 
symbols indicate significant difference from the check. The pretreat- 
ment transpiration rates shown in Table 13 indicate only minor differ- 
ences between the groups of plants in their normal transpiration rates. 

Discussion . --The data presented in Table 10 fail to show signifi- 
cant inhibition of respiration in citrus seedlings sprayed with light 
and heavy oils at a deposit level normally applied for scale control in 
Florida. Although an initial increase followed by a gradual reduction 
in O2 uptake by the plants sprayed with the paraffinic oils and the 
opposite response to the naphthenic oils were indicated, these trends 
were inconsistent and probably could occur by chance. At a deposit 
level twice that of normal field applications (approximately 150 ^ig/bn\ 
the 365-mol wt paraffinic oil significantly reduced the rate of O2 



- ►■ 
uptake (Table 11) 3 and 7 days after treatment. Although conditions at 
the time did not permit further determinations, a trend toward in- 
creased inhibition was indicated. These data are quite limited, but 
they lead to the conclusion that effects on the respiratory process are 
associated with increasing oil deposit and increasing oil heaviness. 
These factors would tend to place more oil on and in the leaf and hold 
it there for a longer period of time. 

The results presented in Table 12 and Figures 14 and 15 show that 
the transpirational process of citrus may be more markedly affected by 
normal rates of oil application than the respiratory process. Also, a 
direct correlation is indicated between oil heaviness, particularly as 
measured by distillation range, and inhibition of transpiration. A 
significant reduction in transpiration was associated with all 6 oils 
the first several days after treatment. The plants sprayed with the 2 
lightest fractions, i.e., 285 mol wt, showed the least initial reduc- 
tion and also the fastest recovery rate. Of these two oils, the 
fastest recovery was associated with the naphthenic fraction. The data 
in Table 3 show that the paraffinic fraction had a higher distillation 
range than the naphthenic fraction. The difference in the recovery 
rates associated with the two 320-mol wt fractions were even greater. 
The recovery pattern for the 320-mol wt naphthenic fraction was nearly 
the same as that for the 285-mol wt paraffinic fraction. The 320-mol 
wt paraffinic fraction depressed transpiration throughout the 70-day 
period to about the same extent as did both 365-mol wt fractions. The 
most peculiar aspects of these curves are that the P-365 oil had less 
effect on transpiration the first few days following treatment than did 
the P-320 or N-365 oils, and that the plants sprayed with N-285 showed 



86 

significant increase in transpiration on certain days beyond the twenty- 
fifth. 

The results discussed above are in general agreement with reports 
of other workers. Wedding et al . (98) reported significant reduction 
in both respiration and photosynthesis in 'Washington' navel orange 
leaves with a California medium-grade naphthenic oil at 150 |ig/cm . 
Photosynthesis was affected to a greater extent than was respiration. 
However, Riehl and Wedding (57) reported no consistent inhibition of 
photosynthesis in lemon or lime leaves by California light-medium or 
medium-grade spray oils at the same deposit level. But a definite re- 
lationship between inhibition of photosynthesis and increasing oil de- 
posit was established (57, 59). Recovery was faster in plants sprayed 
with naphthenic oils than in those treated with paraffinic oils, but 
the paraffinic oils used were of a higher boiling range and the de- 
posits were probably more persistent. 

Riehl et al. (56) obtained a two- thirds reduction of transpiration 
in citrus by a California medium-grade naphthenic oil. They concluded 
that the effect on transpiration was due to physical interference by 
the spray oil on or in the leaf tissue and that recovery of transpi- 
ration occurred with dissipation of the oil from the leaves. Full re- 
covery occurred in 3 to 5 weeks after application (56). Recovery was 
faster in plants sprayed with a naphthenic oil than in plants sprayed 
with a paraffinic oil of comparable molecular weight (58). However, 
the paraffinic oil had a 50% distillation temperature of 663 F while 
that of the naphthenic oil was only 642 F. Table 3 shows that the 50% 
distillation points of the 285, 320, and 365 molecular weight fractions 
used in the present study were 1) naphthenic: 635 F, 689 F, and 738 F; 



87 

and 2) paraffinic: 646 F, 715 F, and 752 F, respectively. 

Distillation range should be stressed because of its relation to 
the volatility of an oil. Because of this relationship, the dissipation 
rate of oil deposits from citrus leaves and fruit should be inversely 
related to the distillation temperatures of the oil. The importance of 
oil evaporation rate with respect to insect control was discussed ear- 
lier. Apparently, the adverse effect of oils on the physiological 
processes of citrus trees is closely associated with endurance of the 
oil deposit. Thus, insecticidal and phytotoxic properties of oils are 
closely related. 

The transpiration measurements made in this study are probably 
most important as indicators of the endurance of oil deposits and of the 
depressive effect on the other processes discussed — respiration and 
photosynthesis. Riehl and Wedding (57) showed that the reduction of 
these processes was due to physical interference with gaseous exchange 
caused by the presence of the spray oil in the tissue and not to death 
of the cells. The principal effects occurred in the tissue of the leaf 
marked by the dark discoloration known as oil-soaking. Tests with 
tetrazolium showed the cells of the discolored tissue were not killed. 
Recovery of physiological processes accompanied dissipation of the oil 
deposit. Inspection of the response curves for the 285-mol wt paraf- 
finic and the 320-mol wt naphthenic fractions in Figures 14 and 15, 
reveals striking similarity in the recovery patterns after the tenth 
day. Assuming that this pattern of response is intermediate between 
temporary and prolonged physiological effects on the citrus plant, the 
distillation temperatures of these 2 oils offer a reasonable approach 
to the selection of an optimum distillation range with respect to plant 



• . 88 

safety. As mentioned above, the 50% distillation points for these 2 
oils are 646 F and 689 F, respectively. However, these are laboratory 
determinations; if field conditions are considered, the effects of 
weathering factors might increase the dissipation rates to the extent 
that the above distillation temperatures could be increased considerably 
without drastically increasing the effects of oil on the physiology of 
the citrus tree. Comparison of the resulting temperatures with the 
minimum distillation temperatures for efficiency against citrus pests 
derived from Figures 9 and 13, reveals some interesting possible corre- 
lations between insecticidal efficiency and plant safety. 
Oil blotch, leaf drop, and fruit drop 

Results . --Treatments were applied when the fruit were in the stage 
of highest susceptibility to oil blotch. Inspections of the fruit were 
made on the tree throughout the season and at harvest time. Although a 
variety of oils were applied at a heavy dosage, no fruit were found to 
exhibit this condition. 

Weekly leaf drop in grams per 4-tree plot for each treatment is 
presented in Table 13. The accumulated leaf drop for the 5-week period 
is shown in Figure 16. It is readily apparent that a higher rate of 
drop occurred in the treated plots than in the check plots. The great- 
est portion of the leaves dropped during the first 2 weeks in the 
treated plots, with the rate gradually diminishing up to the fifth 
week. At this time a reversal in the relative rates of leaf drop oc- 
curred. Whereas the check plots and the plots sprayed with the 60-SSU, 
high-UR oil, R-60, had the lowest rate of drop during the first 4 weeks, 
they now showed an increased rate, and the plots treated with the 74- 
and 92-SSU, high-UR oils, P-96 and BR-1, showed a relatively low rate 



89 



O 

o 

1—1 
PQ 

C 
•H 

vO 






c 
o 

CO 

a 

CO 



o 

c 
o 

•H 
4J 
CO 

o 



c 

•1-1 



o 

CO 
(1) 

0) 

1-1 



PS 



00 

§ 

o 
>^ 

o 
u 



to 






1-1 M 
CO -H 
JJ C4-I 
O 

H 



CO 
CO (U 



1-1 in CO 
CO ^ 

o o <u 



4-1 

o 



u 
u 
I 

M 

cu 



60 



o 

CO 
0) 






<f IS 



-o <u 
en S 



T3 0) 

C cu 



4-1 (U 
CO 0) 



CO 

4J CU 

o ^ 

1-1 4J 



c 

CD 

a 

4J 

CO 
(U 
U 

H 



m 


<y\ 


r^ 


1— ( 


o> 


r~~ 


<t- 


CJ> 


CN 


m 


en 


m 



C3^ 


CN 


1— < 


o 


r-~ 


a\ 


<r 


r-( 


in 


vO 


m 


r^ 



at 
in 

CM 

in 



cd 

in 
o 



in 


r~- 


ro 


00 


<!• 


CO 


vD 


in 


CO 


r^ 


v£> 


00 


•\ 




•\ 




1-1 




1—1 





1—1 


o 


CJN 


CJs 


o 


1—1 


0^ 


v£> 


vO 


o 


00 


1—1 


rt 


«s 


•\ 


*% 


i-H 


1— ( 


1—1 


1-1 



•a 



o 
in 



•s 

00 

CT^ 
1—1 
■J- 



in 



~* 


ON 1-4 


vO 


CN 


CN 


^ 1-1 


o 


in 


O 


1-1 o 


CN 


CO 



CM CN CO CN 



^ n t^ -* 

cTi m <J- r-~ 

O CM I-* CM 

CM CN CO CN 



CM 



43 

in 

CM 









JD 








.o 










CO 








O 








o 










o 


00 1-1 

CN CO 


as 
1—1 


CJN 

i-H 


00 
CM 

m 


in 

CM 


CO 
CM 


vO 1-1 

CO 1-4 

CM CO 


C3> 
vO 

at 
o 


CM 


00 


CO 

1—1 


00 

vO 


o 
o 


o 00 

.-1 O 

1— ( 1—1 


CO 

in 


1-4 


.5 a 108. 


o 

1—1 


O 

o 

1-1 


in C?^ 


CT. 

•8 


CM 
CM 


ON 


00 

1-4 


00 

vO 


CTi 
CO 

1-4 

o 

XI 
CN 


vO CN 

i-H 


in 

vD 

1-1 


in 

CJN 


.0 a 112, 


1-1 
00 

1-4 


1—1 


CM m 

r^ O 

f-H CM 


CO 

00 

1—1 

•8 

• 


CM 

1-4 
CM 


CO 

1-4 

CO 


VO 
CM 

in 


o 

r-4 

CN 


m 

CO 

o 
00 


.-< o 

00 c?\ 


CM 
00 


1-1 
C3S 


00 


O 


o 


1-4 in 
CO 00 
in CO 


CO 

in 

CO 


c^ 

i-H 
00 


1-1 
00 


CO 

00 


CN 


m 

CO 

00 



00 in 1^ CM 
CO in <)■ <)■ 



at 



in 



r~ 


o in 


CJN 


1—1 


r~ vo 


1-1 


vO 


CO 00 


CM 



1—4 

in 



CJV 


vO 


<t 


1-4 


vO 


<f 


CO 


o 


r^ 


CT\ 


CO 


CM 






#t 


*\ 






1-4 


t— < 



u 
in 

CN 
vO 

o 



1-4 CN CO ~J 



O 

CU 



1^ 



1-4 CM CO <)• 



(U 



1-4 CM CO -d- 



CU 

2 



o 



vO 
I 



90 



u 




^■^ 




5 


O CO 










'^-^ u ^ 




CM 




CM 


CO <u 




• 




• 


■-1 )-i 0) 


r-i r^ in ^.o 


t^ 


CM in CM o 


1^ 


CO .H S 


O >-l in CJ^ 


vO 


m cy> o o 


CO 


4J 14-1 


m >— 1 r^ cs 


vO 


in 00 --I vO 


o 


O ^ 


«v n n fs 


^ 


M •\ » 


•\ 


H 


>— 1 1— ( i-( CM 


t— 1 


CO rg i-i 


CM 



1-1 in en 

Id ^ 

u u a 

o o <u 

H 4-1 > 



4-> 
O 



(U 

(1) 

4-1 

I 

<!• 

U 

di 



i-i 

00 



o 



(U 

3 

c 



d 
o 
u 
I 
I 

CO 






AJ a) 
in u 






)-i <U 

CO > 



C (1) 

CN 3 






CO 

o u 



■^ vD CN| r~ 
C7^ CO <!■ <)■ 
r^ CO <X> <!■ 



^ 




.0 


00 




in 


• 




• 


■vf 


.-1 00 <N r~. 


>* 


in 


in r~~ CM vo 





00 


00 cy> CO vo 


CM 


•\ 


r\ •» •> 


•* 


,— ( 


CO CM r-( 


CM 



CO C3> r-^ 
<yi .— I 00 in 

CM CN 



•8 



00 



O 



CTi CO O r^l 
0> 00 CM ^ 
CM tN 



•8 






•8 

o 



0^ 



CTN CvJ CM 


r— 1 


T-l 


00 ■* CN 


vO 


CM 


<f <t <!■ 


ON 


CO 


i-( ^ CO in 


CO 


-d- 


CM rH CM 


CM 


Csl 


CO r-( 


r-( 


00 



•8 



o 

o 



in CO (Ti r^ 


00 


CM vD r^ CO 


CN 


00 


00 00 CN CO 





CO CO CM r^ 


<f 


«* 


.-1 CM CO 


CM 


<!■ CM -J- CM 


CO 


vO 



CM CM 


VO 


<1- 


00 in 


vO 


r- 


VO <}■ 


vO 


t^ 



CO 
VO 



CO 
VO vl" 
CO CO 


1-1 

m 


00 




r-i 







o 

m 

m 

VO 



vO 

CO 



in o 00 <r 

00 <t 1-1 ON 

00 -^ vD 00 



1-1 CM CO ^ 



Xt 




^ 


CM 




00 


00 
m 


ON in CM CTi 
CO r^ m vo 
<!■ CM ON 00 

i-i 


CO 

00 

CO 



m 

CO 






.— I CM CO Vt 



c 




(U 




B 


i-< 


u 


1 


cd 


»5 


0) 


CP 


u 




H 








(1) 






s 




CO 

u 

C 




^4 


u 







CO 




l« 


(U 




1—1 


4-1 




tfl 






•u 


I-I 







1— 1 




H 


CO 



in 



(U 



cu 

M-l 



14-1 




•H 




C 




60 




•H 




CO 




4-1 









C 




<u 




u 




CO 




11 




(U 




4J 




4-J 




0) 




1—1 




<u 




1 


4J 


CO 


CO 




<U 


(U 


H 


J2 




4J 


<U 




60 


>N 


c 


J2 


CO 




p:i 


"O 




(U 


0) 


13 


i-H 





a 


1-1 


•H 


i-H 


4J 





i-H 


14-1 


3 




s 


J«! 




(U 


s 


(U 


(U 


3 


^ 


C 


CO 


<u 


» 


> 


s 


•H 


CO 


60 


u 




c 


CO 


3 




Q 


M 










u-t 


4-1 


CO 


60 


g 


c 


CO 


•H 


<u 


T3 


e 


U 







4-1 





c 


U 


<u 


CO 


s 




4-1 


1—1 


CO 


(U 


(U 


> 


^ 


(U 


H 


1—1 



-'^S 



91 




T) 




O 




■H 




U 




<U 




a 




J<! 




OJ 




<u 




S 




1 

u-l 




0) 




J2 




J-l 




Ci 




•i-l 




to 




di 




(U 




M 




4-1 




<u 




60 




C 




CO 




^ 




O 


• 




-* 


— 


v£) 


c 


a\ 


•H 


1—1 


1— 1 




g 


>^ 


CO 


CO 


PC 


S 




vO 


B 




o 


c 


u 


o 


u-l 






10 


CXr-t 


o 


•H 


u 


o 


TJ 






<t 


4-1 




CO 


<4-l 


(U 


o 


,— 1 






c 


•o 


o 


(U 


•I-l 


4-) 


4-1 


n) 


CO 


1—1 


<J 


3 


•H 




I-l 


3 


a 


o 


a 


o 


CO 


<3 






(JO 




c 


• 


•1-1 


vO 


jj 


1—1 


o 




r-l 


01 


1—1 


h 


o 


3 


M-l 


00 





92 

of drop. Except for the third week, the low-UR, 72-SSU oil, BR-2, 
effected an intermediate rate of drop. 

The significance of the differences between the means for- the 
weekly drop rates and the totals for the 4- and 5-week periods are 
shown in Table 13. The differences were greater in the 4-week period 
than in the 5-week period. This can be attributed to the relatively 
high rates of leaf drop that occurred in the check plots and R-60 plots 
during the fifth week. These tended to equalize the total drop for the 
4 oils. All 4 oils effected a significantly higher leaf drop during 
the first week than the check. During succeeding weeks the differences 
became less significant. 

The weekly fruit drop in numbers per 4- tree plot is presented in 
Table 14. No significant difference was detected the first week, but 
after this time, P-96 and BR-2 effected significant drop throughout the 
5-week period. The light, highly-refined oil, R-60, caused no signifi- 
cant drop at any time. The relationship between treatment and fruit 
drop seemed to be the same as that for leaf drop. However, there was 
no indication that the total amount of drop in the check plots would 
eventually equal that of the oil- sprayed plots. 

Discussion . — Although no evidence of oil blotch was obtained in 
this experiment, considerable leaf and fruit drop was effected by the 
various oils. With respect to distillation temperatures, the 4 oils 
consisted of 2 light oils (R-60 and BR-2), 1 medium oil (P-96) and 1 
heavy oil (BR-1). Of the 2 light oils, 1 was highly refined (96.1 UR) 
and the other was of low refinement (85.0 UR) ; the medium (74.3 vis- 
cosity) and heavy (92.5 viscosity) oils were both highly refined (95.6 
and 94.0 UR, respectively). With respect to molecular weight and 50% 



93 



Table 14. Fruit drop by young 'Hamlin' trees following application of oil 
sprays on 6 May 1964 in Block 23 





Plot 




Number 


of fruit 


per 4- 


tree plot^ 






1st 


2nd 


3rd 


4 th 


5 th 


Total 


Treatment 


(4 trees) 


week 


week 


week 


week 


week 


for 5 
weeks 


Check 


1 


45 


39 


5 


1 


2 


92 




2 


15 


35 


3 








53 




3 


13 


19 


1 


3 





36 




4 


24 


26 


2 


4 


3 


59 



Mean 

R-60 . 1 
2 
3 
4 

Mean 

P-96 1 
2 
3 

4 

Me an 

BR-1 1 
2 
3 

4 

Mean 

BR- 2 1 
2 
3 
4 

Mean 

Weekly total 

for all treatments 



24.2 a 

55 
30 
38 



30.8 a 

53 

109 

24 

37 



29.8 a 

150 

52 

101 

1 

76.0 a 

157 
237 
143 

89 



2.8 



2.0 



55.8 a 156.5 b 



32 

46 
23 

41 



74 
87 
95 
86 



35.5 a 85.5 ab 



38 
36 
29 
18 

30.2 



706 



192 
53 

103 
77 



10 


16 


13 


5 


10 


7 


5 





9.5 a 


7 


58 


19 


51 


15 


51 


44 


41 


7 


^" 




50.2 c 


21 


24 


17 


14 


18 


39 


15 


19 


22 


■— ~" 


— 


24.0 b 


18. 


52 


51 


44 


7 


46 


32 


34 


11 



1.2 

3 

I 
2 



60.0 

234 

100 

157 

8 



.0 ab 1.5 ab 124.8 ab 



4 

5 
1 



291 
412 
267 
175 



2.3 ab 286.2 c 



6 

7 

4 

11 



153 
172 
176 
179 



7.0 ab 170.0 ab 



33 


366 





140 


22 


232 





140 



106.2 b 44.0 c 25.2 b 13.8 b 



219.5 be 



1,816 



522 



294 



104 



3,442 



n?f,v!^M ^'^?? ^""^ ^ ^^''^'' ^^"^ followed by the same letter are not sig- 
RangeTest. "' '' '"' ''' '^"^' ^^^°^'^"^ ^° °— "^ New Multiple' 



't' -^^ ' ^ ^ ^" ■■ ^ 94 



distillation point the 2 light oils were similar, but the low-refined 
oil had a viscosity of 71.7, due mainly to the aromatic content (13. 6%) 
and to the heavy components in the upper portion of the 10 to 90% dis- 
tillation range. Comparisons may be made, therefore, on the basis of 2 
important oil properties--heaviness and refinement. 

With respect to oil heaviness, increased leaf drop was associated 
with an increase in oil heaviness from the light to the medium range 
but not from medium to heavy. This is in agreement with Thompson's 
(84) report that no increase in leaf drop on Florida citrus occurred 
with increase in viscosity from 72 to 100 SSU. However, the data in 
Table 13 indicates less leaf drop in favor of the 60-SSU oil in the 
first 4-week period. Riehl et al. (51) reported that increase in leaf 
drop following oil sprays may accompany increase in oil heaviness from 
200 to 350 mol wt . Smith (72) found that the amount of leaf drop was 
related to the weight of the oil as indicated by the distillation 
range, and to the quantity of oil deposited on the foliage by the spray 
mixture. The data for the light, low-refined oil is in agreement with 
reports of California workers (24) that leaf drop is indirectly related 
to UR, or refinement, although Thompson (84) reported no difference be- 
tween oils of low and high UR with respect to "shock to the tree" in 
Florida. However, he worked with oils of 70 viscosity and higher and 
any effect on leaf drop due to refinement might have been masked by the 
effect of oil heaviness. 

The data for the fifth-week count of leaf drop are interesting in 
that the checks showed a significantly high drop rate. This, plus the 
fact that the rate of leaf drop effected by the heavy oils and the low- 
UR oil had diminished to a significantly low level by the fifth week. 



95 

indicates that over a longer period of time the total leaf drop would 
be about equal for both sprayed and unsprayed trees. Perhaps the oil 
merely hastens an inevitable process. It is interesting to note that 
no leaf drop followed the second application of the oils to the same 
trees in September. 

The data in Table 14 show that fruit drop resulted from the oil 
application. From the data presented, it is difficult to relate this 
drop to any particular property of the oils. The plots treated with 
the 74-SSU oil and the low-UR oil were consistently high in fruit drop 
and the rate was significantly higher than that of the check, except in 
the first and fifth weeks. The light and heavy oils were not signifi- 
cant from the check for the total 5-week period. However, after the 
first week, the rate of drop associated with the light, highly refined 
oil was lower than that caused by the other oils. 

The time of application of these oils was about 5 weeks prior to 
the normal "June drop" of fruit in Florida citrus, during which the 
trees shed about 20% of the crop. However, the checks did not indicate 
that the fruit drop following these treatments was associated with the 
June drop. Ebeling (24) discussed the problem in California. Oil 
sprays are normally applied to citrus in that state beginning in late 
July, after termination of the normal "June drop" period. Beginning 1 
or 2 weeks after spraying and continuing for a month or more, a heavy 

fruit drop amounting to as much as 50% or more was caused or accentu- 

^ ' ■- 

ated by the oil spray. The effect was unpredictable and was not found 
to be related to any particular predisposing factor. He quoted the 
following statement from Smith (72): "Drop has occurred when the soil 
moisture was high, when it was moderate, and when it was low. In many 



96 



cases groves appearing to be in excellent condition have suffered as 
heavy drop as those which appeared to be in a poor state of vigor." 
Fruit color and ethylene degreening 

Results . --The fruit samples harvested 16 October and 12 November 
were degreened with ethylene gas for 72 hours. The color of the fruit 
was measured after 0, 24, 48, and 72 hours exposure to the gas to de- 
termine the degreening rate. The color values obtained for the differ- 
ent samples at each of the 4 readings are presented as per cent ab- 
sorbance in Table 15. Each value is the average of measurements on 
40 fruit. Per cent absorbance is directly related to the amount of 
green color in the fruit peel. As indicated by the letters adjacent 
to the treatment means for each time of degreening on each sampling 
date, fruit from oil-sprayed plots were significantly greener than the 
check fruit at harvest, and this relationship held throughout the 72- 
hour degreening period with only 2 exceptions. Fruit from trees spray- 
ed with P-96 degreened to the same level as check fruit in the 4-week 
sample and fruit from trees treated with R-60 did likewise at the 8- 
week sampling. However, the effect of P-96 should be viewed with some 
skepticism since a temporary fault in the sprayer at the time of appli- 
cation resulted in a dilution of the spray and a low, unknown level of 
oil deposit. Closer inspection of the data for the 4-week sample shows 
the 72-SSU, low- UR oil, BR-2, and the 92-SSU, high-URoil, BR-1, had 
the greatest adverse effect on color. This same relation held at har- 
vest time for the 8-week sample but after 24 hours degreening no sig- 
nificant difference existed between the oils, although all oil- treated 
fruit were greener than the check fruit. 



0) 

c 

(U 
1-1 

>>. 

J2 



n-i 
o 



CIt 

> 
u 

(U 

c 

•H U 

a 00 



0) 



M-l (0 
M-t U 

•H a 

h h 
(U <u 

4J 4J 
CO CO 

"a CO 
£ -^ 

CO (U 

(U u 
l-l 

C» 

^ c 

CO 
CO 

(1) <J- 
bO 

C -u 
CO CO 
U 
o u 

- o 

C I 

••-I X 

.-I CJ 
S CO 

co a 
w 

- 4J 
C 

•a <u 
(u u 

>^ 

CO M 

)^ (U 

CO 

1 T3 

--< C 
•H CO 
O 

bO 
H-l C 

c 

(U 

(U 

60 
O (U 



CO 



o 



J2 
CO 
H 



C J-' to 
<U I CO ^ 



U 4J 

^1 CO 3 

0)0.0 



0) 
(U 
IS 

C30 



CO 

<u 
<1) 

? 

00 

i-> 
CO 

o 

t-l 
o 
o 

c 

0) 
60 

> 

•H 
4J 

CO 

.-I 

0) 

Pi 



c 

CO 



T3 



CO 

CJ 

•H 

1-H 

a 
Pi 



fO 



c 




4J 


CO 


0) 


1 


CO 


^ 


o 


^ 




<u 




u 


U 


(U 


^ 


CO 


3 


s 


(U 


& 


O 




PM 






■<r 



CO 
01 



4-1 

CO 

;^ 

O 
I— I 

o 

o 

c 
<u 

60 

> 
•1-1 
4-1 
CO 

r-( 
<U 



c 

CO 



4J 

CO 

CJ 



p. 





CO 4J 




<U c 




>-l 0) 




H B 




to 


c 


c 


•H 


•H ^1 




C 0) 


CO 


<U ^ 


^J 


<u e 


3 


^1 CO 


O 


60 x: 


P3 


<U o 




XI 



^■^FTT-i- 










97 


1 1 1 1 1 

o 


1 1 1 1 1 


1 


1 1 


1 1 




CO ^ XI XJ U 


CO X X X X 


CO 


X X 


X X 




r~ r^ T-H \o O 


<!• m CM o en 


O 


O CJN 


00 <s- 




in <f <» u-i <f 


in CM 00 CO o 


en <j- NO 


CM <3N 




in (T) in i-< 00 


vO r^ 00 r-. <N 


CM 


CJN O 


(3N .* 


r^ 00 00 00 00 


in vo vo vo p^ 


cn 


m <f 


cn >* 




1-1 rv o <t 00 


O CN r^ <7N On 


in 


•<!■ 1-1 


vO f) 




O 00 .-1 in o^ 


nd in cjN ON o 


ON 


r~ 1-1 


o m 


r~ r^ 00 r~. r~ 


in vo NO in c^ 


CM 


m o- 


cn -d- 




00 CO ro 00 o 


in <j- ON CM r-~ 


1—1 


<f r~. 


P-. in 




Csl CO G^ 00 ro 


■4- o en r^ 1^ 


00 


cn <!■ 


00 o 


r^ 00 [^ r^ 00 


in r^ NO NO vo 


CM 


■<r cn 


cn >j 




r^ 00 ^ 00 O 


1-1 <f O C3N CM 


m 


C3N CO 


r~- m 




r^ 00 i-H r^ 00 


vO ON O CM 1^ 


in 


O CM 


in CM 


t^ 00 ON oo-o 


in NO 1^ r^ r^ 


cn 


<f <t 


<!■ in 




vO (N 00 ro p^ 


NO O r^ CM <!• 


-* 


00 CM 


1-1 p>. 




1-1 CO 1-1 <f CM 


CJN <t 1-1 ON CM 


NO 


in vt 


CM CO 


00 00 e3> 00 cy. 
1 1 1 1 1 


in NO r^ NO r^ 
1 1 1 1 1 

CJ 


cn 

1 


cn <t 
1 1 

t3 


1 1 




cfl X XI X X 


CO X U X o 


CO 


o o 


X 13 




o in o o CM 


CM O O CM CM 


r-- 


in in 


CM r» 




r-~ en 1-1 r^ <f 


O- <f <t CJN vO 


O 


in CJN 


CM <r 




in 1— 1 cs cy\ o 


CM 00 On in 00 


r~. 


m NO 


rH ON 


00 ON 0^ 00 0^ 


vO NO NO nO nO 


m 


<J- <f 


<t <r 




C3N vO <f 00 CM 


1^ o en ON <)• 


in 


r^ 1-1 


O NO 




<f r^ O vo 00 


1-1 in in 1-1 in 


•vf 


CM CM 


00 00 


00 00 CTi 00 00 


vO vO nO nO nO 


cn vj- <j- 


rn -^ 




CT\ <)■ r^ vo c~. 


m <}■ i-( <j- o 


CM 


NO O 


CM -* 




<J" 00 c?N r^ ON 


cjN NO o en NO 


in 


m 00 


NO NO 


00 00 CO 00 00 


in NO 1^ NO NO 


cn ^ <f 


m <)• 




O r^ 00 r^ ~d- 


i-i o ON r-~ 1-1 


NO 


CM O 


ON 1-1 




00 <f CM 1-1 CM 


m CM C3N 00 CM 


o 


00 NO 


CM cn 


CO ON ON ON On 


NO 1^ NO NO f^ 


<t 


-* <)■ 


-d- in 




o r~ in t^ -d- 


NO CM en t^ o 


o 


r~ r^ 


00 00 




in <)■ in CM 1-1 


in o CM C3N 1-1 


00 


r-. r-< 


r^ C3N 


00 ON ON ON ON 


NO r^ r^ NO r-~ 


cn 


<t in 


<r <!■ 




^ 


M 


M 








O O CM vO i-( 


O O CM NO 1-1 


o 


O CM 


NO 1-1 




Q> NO 1 ON 1 


OJ NO 1 CJN 1 


(U 


NO 1 


C3N 1 




x: . P=i 1 oi 


x: 1 cc; 1 pc; 


X 


1 05 


1 Pi 




U 05 PQ f^ PQ 


U OS pq PM P3 


u 


Pi m 


Pm pq 




O 


St 




00 







lU 
3 
C 
•H 
4-1 

c 
o 
u 
I 
I 






4-1 

c 



U 
l-i CO 

0) a. o 



(U 



4-1 

3 



00 



(0 

0) 

00 



(U 

c 
cd 

g 






c 




4J 


03 


<u 


1 


CO 


^ 


o 


^ 




<u 




U 


4-1 


<u 


u 


to 


3 


? 


OJ 


& 


O 




Pli 






<J- 



CO 

cu 



4-1 

CO 

u 

O 

i-H 
O 
U 

C 
(U 
(U 

^^ 

00 

> 

•1-1 






0) 

c 

CO 

s 



(U 
4J 

CO 

o 






I 

4-1 

CO 4-1 

<u c 

M (U 



60 

c c 

CO <U 43 

V4 <u e 

3 ^1 CO 

O M jn 

S 01 U 

T3 



''■ .' ' 










N S 


98 


.1 










f 




o <f <r o 00 










• , • 




■ • ■ • • 




, 




^ 


, **i 




O CJN CJs O 00 










' » 




O c?N CT^ O 0> 










-IN 




r-( l-H 










•rl 




^ 




.)■■ 






>. 




CO CO XI XI J3 




-;* 


^ 




4J 




00 -<)■ vO >^ <)• 










s 




vD vO 1-1 <t ro 






















U 




i-H u-i r^ r^ O 










t* 




(N CN CM CM en 














<t vO lA vD O 






















vl 




cj> <r vo <)• r~. 










(S 




i-H CM CN CN fSI 














00 <N vO CM O 












• • • • • 














r^ ON CO ctn r^ 


• 








« 




1-1 CM CM CN CM 


en 

(U 
CO 








^ 




vO CM i-< CM <)• 


CO 








4> 




<f >^ ON vO 00 


U 








W 




CM CM CM CM CO 


o 

(U 
"0 


• 

c 
o 






CU 

1-1 




CJ> r^ <]• O cj\ 


M 


•H 
4J 






01 4-1 




<}■ <N CJN O 00 


O 


CO 






S CO 




CM CM CM CO CM 


i-H 
O 

u 


4J 
W 

4-1 






CO QJ 
CO H 

OJ OJ 




<f o <!• i-H in 




c 

QJ 






x: 60 

4-' C 




On LO <JN 00 r~. 


a) 


B 


■ 




CO 




ON ON 00 ON 00 


u 


•H 


CO 




>^ B5 






60 


V4 

Q) 


T-l 

CO 




X3 
OJ 






CO 


D. 


> 




•a 1-4 






CO 


X 


u 




OJ (X 








w 


Oi 


• 


? •H 




o 


CO 




u 


4J 


O 4-> 




CO X3 J3 CO u 


<u 


CO 


a 


•H 


1-1 1-1 






CO 


3 


•M 


3 


1-1 3 




CM o r^ r^ O 


CO 


1-1 




U 


o S 




o NO -d" NO vo 


(U 


4J 


u 


U-l 


>4-l 




• • • • • 


^4 


•1-1 


3 




5 




NO CO in 00 cjN 


CJ 


u 


o 


o 


•a QJ 




CM CO CO <N CO 


0) 

•a 


•\ 


1 


<)■ 


o z 

•H 








CO 


<r 


S 


M CO 




00 ^ 00 m <!• 


o 


CM 


CN 


o 
u 


0) - 

(X c 




1-1 o 00 in ON 


C 


^ 


4-J 


4-1 


CO 




CM CO CM CM CO 


CO 


o 


CO 




60 U 






XI 


o 




CO 


c c 






^4 


1—1 


4-1 


60 


•H 3 


* 


NO in <j- <)■ <f 


o 


pa 


•1-1 


C 


C Q 




• • • • • 


CD 




3 


•H 


QJ 




NO O NO CO <f 


XI 


• n 


U 


•o 


QJ O 




CM CO CO CM CO 


CO 


NO 


>4-l 


CO 

QJ 


^4 4-t 
60 






■ r\ 


C3N 


QJ 


M 


OJ 60 




<N NO <f CJN 1-1 


a 


i-H 




U-l 


T3 C 
•1-1 




ON (^ in ON <i- 




M 


CO 


O 


C T) 




CM CO CO CNj -d- 


in 


Q) 






0) ^1 






t^ 


•e 


QJ 


QJ 


> O 






NO 


s 


x: 


60 


•H U 




in CM CO <JN m 




QJ 


4-1 


CO 


60 O 






4J 


4J 




U 


CO 




NO NO 1—1 in o 


CO 


a 


c 


QJ 


CO 




CN CO <t CO vd" 




QJ 


o 


> 


*i 






OJ 


Vi 




CO 


)-i 1-1 






o 




QJ 




O QJ 






c 


00 


T3 


QJ 


C4-I > 




^ 


CO 


1—1 


CO 


x: 


QJ 




O O <N NO 1-1 


XI 




E 


4-» 


CO 1—1 




(U NO 1 CJN 1 


u 


T3 






C 




x; 1 (Si 1 BS 


o 


OJ 


QJ 


CO 


CO s~? 




U Di PQ Oi PQ 


CO 


■1-1 


h 


•f-l 


QJ in 






XI 


i-< 


CU 




E 






CO 


a 

a 


> 


QJ 

3 


OJ 
4J XI 






4-1 


CO 


CO 


r-l 


C 4J 






c 




60 


CO 


0) 






QJ 


CO 


c 


> 


e 4-1 


i 


CM 


O 


>N 


•1-1 




4-) CO 




r^ 




CO 


Xl 


XI 


CO 






u 


M 


CO 


o 


01 4-1 






QJ 


& 


(U 


CO 


U C 






PU 


CAl 


BJ 


w 


H QJ 






CO 


J3 


u 


T3 


QJ 





99 

A direct linear relationship exists between degreening as measured 
by this method and exposure to ethylene gas up to 72 hours, but a tend- 
ency toward curvilinearity after 48 hours was indicated. This is shown 
graphically in Figures 17 and 18 where per cent absorbance is plotted 
against degreening time in hours. The degreening rate for the fruit 
from each treatment was calculated as the regression coefficient of the 
respective curves in these 2 graphs. This is the "b" value in the re- 
gression equations presented in Table 16. The greater the negative 
value for "b," the faster is the degreening rate. Ninety-five per cent 
confidence limits were calculated for each "b" value and where these do 
not overlap the degreening rates are considered significantly different. 

The four 40- fruit samples for each treatment were graded for pack- 
out with respect to color after the 72-hour degreening period. The per 
cent pack-out for each treatment on the basis of the 160 fruit is given 
in the last column under each of the sampling dates in Table 15. These 
values indicate the relationship between the absorbance readings and 
pack-out. The critical value for 98% or better pack-out appears to be 
about 307„ absorbance. On the basis of this apparent relationship, the 
regression equations for each treatment were used to calculate the hours 
degreening time required for the fruit to attain the 30% absorbance 
level. These values are presented in Table 16. To supplement the 
numerical data on degreening rates, a pictoral record was also obtained. 
The photographs in Figure 19 show the appearance of 16- fruit samples 
for each treatment on the 2 sampling dates degreetied for 0, 24, 48, and 
72 hours. 

Discussion . --The data presented in Table 15 support the long- 
recognized fact that late oil sprays affect the degreening rate of 



r^S^-T^ 



100 



a 
I o 

o o 



o c 

(U 
0) 0) 
4-1 M 
to 60 
U 0) 

•a 

00 

c o 

•H -U 
C 

(U -o 

0) 0) 
00 ■!-( 

•a cr 

lU 
M 



0) 
4J 
U 

o 



CO 
M 

3 
O 
M-l X 

M -a 
C 6 



o 


(3 




•H 




CO 


4J 


CO 


1-1 


(0 


(U 


(U 


3 


oc 


> 


cr 


c 


<u 


(U 


CO 


1— ( 


a 


O 


0) 


o 




u 


•1-1 


Mi 


c 


CO 


B 


CO 


CO 


•H 


^ 


(U 


r-l 


U 


)-l 

00 


1 


o 

CO 


Oi 


33 


.o 


Q!^ 




CO 






CO 




(U 


l-l 




<u 


3 


o 


u 


o 


4-1 


00 


PC 







00 

a 
•1-1 

CO 

u 
a 

CO 
<U 

4J 

m 

CO 
CO 

<u 

» 



CO 
43 



U 

o 









XI 

+ 



II 



>3- cTi vo m ro 

r^ i-H in CO vD 

CN CM ^ vO o 

\0 r^ r~^ ^ 00 



t-» m vo o 
CN CO o o 



fO 

fo 



•S 

CO ja 43 



CO o 



vO vO i-i r^ fO 

t-l r^ O CM CM 

CN c^ 00 -J- c^ 

00 r^ I — 00 vD 



I 



I 



I 



o o o o o 

4-1 4J 4-1 4-1 4J 

o -J- in iTi fo 

r^ CM ^ fO 1-4 

CO -^ CN CJS ^d- 

00 00 00 00 r^ 



I I 



I 



s 

u 

CO 
(U 

u 

H 



X X X >< t< 

n o en 1-1 00 

<)• O fO 00 vO 

m CM O vD 1-1 

00 00 00 CO r— 

I I I I I 

vO CM On vO 00 

00 0^ ON r^ r^ 

00 00 00 00 00 



O O CM vO ^ 

V vO I C7N I 

x: I (Ki I pel 

(^ DS PQ PL, PQ 



00 

c 

•1-1 

CO 

M 
(U 



CO 
4<i 
0) 
<U 

00 



CO 
43 

U 
O 

14-1 

d 

m 



X 

43 
+ 
CO 

II 



• • 


• • 


• 




CO 


r- <>• 


vO vO 


o 




> 


m vo 


vO vO 


r-~ 


1 
§ 


44 

c 

1-1 

u 

c 

0) 


43 


u 


43 


<u 


T3 


O CO 


CO 43 


CO 


44 
44 


•H 


vO m 


CO 00 


00 


a> 


c 


>* ^ 


O <t 


m 


1-1 


o 


in CM 


CO vO 


CM 




u 


r^ 00 
1 1 


CO r-~ 

• • 

1 1 


00 

• 


i 

CO 


m 

Ov 


o o 


O 


o 






44 44 


44 44 


44 




•1-1 


<t <3\ 


r-l O 


vO 


u 


(U 


(J\ CM 


>* vO 


r^ 




42 


a\ vo 


r^ CM 


in 


P^ 44 


r^ 00 


00 00 


00 

1 


43 
X) 

o 
1-1 

1-1 

o 

<4-l 


(U 

o 

c 

•1-1 

CO 

44 

c 


X X 


X X 


X 


44 


O CM 


CM -J- 


CM 


O 


■4-1 


r~ f\i 


CM m 


i-H 


c 


144 


r^ >* 


m cjv ^ 




•r-l 


r- 00 

• • 


00 r^ 

• • 


00 

• 


CO 
44 

s 


•a 

f-i 


in CN 


CO m 


C>J 


• • 


• • 


• 


•H 


44 


>* ■* 


vO CN 


<T\ 


U 


d 


r^ 00 


00 00 


00 


•1-1 
<4-l 
>4-l 
0) 
O 
U 

•H 
CO 


d significa 
overlap. 


4^ 






w 


(U 4-1 


U O 


CM VO 


■-H 


0) 


u o 


0) vo 


1 OV 


1 


u 


m c 


4r 1 


Pi 1 


OS 


00 -o 


o Pd 


m PM 


pa 


PS 


•H O 
CO "O 



101 



T 1 — r 



T 1 r 



90 



80 - 



6 
m 

^ 70 

O 



§60 



.5 

H 

Z 

u 
o 

M 

I 

I 

OJ 

o 
hJ 
o 
u 

M 



50 



40 



U 



30 



20 




O Check 
A R-60 
O P-96 
D BR- 2 
O BR-1 



24 



48 



72 



HOURS DEGREENED 

Figure 17. Degreening rate of oil-sprayed 'Hamlin' oranges 4 weeks 
after spraying as indicated by decrease in per cent absorbance with 
time in ethylene degreening chamber. Sprays applied 18 September 
1964; fruit harvested 16 October 1964. 



102 



90 



80 - 



a 

in 

H 
<J 

U 
O 



70 — 



T r 



T 1 r 



o 60 

CO 



w 
u 

M 
PM 

is 

o 

o 
o 






50 



40 



30 



20 



1 1 r 




O Check 
^ R-60 
P-96 
D BR- 2 
9 BR-1 



24 



48 



72 



HOURS DEGREENED 

Figure 18. Degreenlng rate of oil- sprayed 'Hamlin' oranges 8 weeks 

after spraying, as indicated by decrease in per cent absorbance with 
time in ethylene degreening chamber. Sprays applied 18 September 
1964; fruit harvested 12 November 1964. 



103 

early oranges. They also indicate that the extent of the effect might 
be related to oil heaviness. That all 4 oils delayed degreening on 
the tree is evident from the significance tests of the color readings 
taken before ethylene degreening (zero hours) , both 4 and 8 weeks after 
spraying. The data for the 8-week sampling indicates that color de- 
velopment was retarded more by the low-UR oil and the high-viscosity 
oil than by the other treatments. The effect of the oils on the rate 
of degreening with ethylene is shown by the data for 24, 48, and 72 
hours degreening time. Considering the 4-week sample, differences 
between oils were detected after 24 hours; these differences were 
accentuated at the 48- and 72-hour readings. Inspection of the re- 
gression coefficients in Table 16 for the 4-week samples reveals that 
the fruit sprayed with 3 of the oils degreened at a slower rate 
than did the check; the rate for the fruit sprayed with the heavy oil 
was significantly lower than that of the check. It is noticed that the 
regression coefficient for the medium oil, P-96, is slightly, but not 
significantly, higher than that of the check. However, it should be 
pointed out again that due to faulty application of this treatment, it 
is not known what the actual oil deposit was relative to the other 
treatments . 

The data in Table 15 for the 8-week sample show that the initial 
on-tree differences in color of the oil-treated fruit were rapidly 
overcome by ethylene degreening. Although color differences between 
check and treated fruit remained significant through 72 hours degreen- 
ing, except the light-oil samples which were not significant from the 
check after 72 hours, no differences were detected between oils. How- 
ever, the mean color readings favor the light oil, R-60, for least 



104 

adverse effect on degreening rate. The fact that the fruit from the 
plots sprayed with the heavy oil and the low-UR oil overcame the 
initial on- tree color differences after 24 hours degreening indicates 
differences in rates of degreening with ethylene gas. The regression 
coefficients in the equations in Table 16 for the 8-week samples indi- 
cate that the oil- sprayed fruit degreened at a faster rate than the un- 
sprayed fruit. However, the differences in on-tree color, i.e. the "a" 
values in the regression equations, were so great that this increased 
degreening rate was insufficient to overcome the color differences in 
72 hours. 

The faster degreening rate of the oil-sprayed fruit is illustrated 
in still another way by the data in Table 16, perhaps having some 
economic importance. The time required for the fruit to degreen to a 
desirable color level was calculated by the regression equations. The 
spread between the check and the heavy oil was 18 hours for the 4-week 
sample; this was reduced to 13 hours for the 8-week sample. The dif- 
ference is amplified even more if the difference in the "a" values, or 
on-tree color, are considered. The fruit from the heavy-oil treatment 
were only 5% greener than the check fruit at 4 weeks but were almost 
20% greener at 8 weeks. This brings out still another interesting ob- 
servation. Comparison of the "a" values for the fruit treated with the 
heavy oil at 4 and 8 weeks after spraying indicates no on-tree color 
break during this time interval. Since this statement is contradictory 
to the appearance of the fruit in the photographs in Figure 19, it 
should be pointed out that the photographs were taken 4 days after the 
fruit were harvested and apparently some degreening had occurred with- 
out the aid of ethylene gas, although the fruit were stored at a 



105 





B8 ^B BS iB&i& 




31 — — 41 





8 -26 28 ?p 32 





Figure 19. 'Hamlin' oranges from plots receiving late-season applica- 
tion of 4 oils and degreened for 0, 24, 48, and 72 hours; sampled 
4 and 8 weeks after treatment. Sprays applied 18 September 1964. 






106 

temperature of 40 F during the first 3 days. 

Extension of the regression equations in Table 16 to the calcula- 
tion of the number of hours of ethylene degreening required for the 
fruit to acquire satisfactory color shows further evidence that oil 
heaviness is a factor in the adverse effect of oil sprays on degreening 
rate. Although all oil- treated fruit required a considerably longer 
period to degreen than the checks, the difference between the light and 
heavy oils was also wide, in favor of the light oil. This becomes es- 
pecially important for the early sample since the fruit from the light- 
oil plots attained the 30% absorbance level in 72 hours (normal maximum 
time for commercial degreening) and the fruit from the heavy-oil plots 
did not. The difference in effect on degreening between the light and 
heavy oils is reflected in per cent pack-out after 72 hours degreening 
(Table 15). The photographs in Figure 20 reveal a little more green 
color after 72 hours degreening in the fruit treated with the heavy oil 
than in the fruit from the other treatments, even in these very limited 
samples. 
Internal fruit quality 

Results . --The results of the fruit quality analyses are presented 
in Table 17, These include per cent soluble solids, per cent acid, 
solids/acid ratio, and per cent juice for all treatments on the 4 
sampling dates, and the average fruit diameter for each treatment for 
the first 3 sampling dates. Significance of the differences between 
means on a given date are indicated. No differences occurred for any 
of the factors measured other than solids. The rate of increase in 
soluble solids for each treatment with time after spraying is shown 
graphically in Figure 20. The horizontal broken line in this graph 



107 



o 

60 

to 
u 



(U 



to 

•H 

B 

to <!■ 

W ^ 
0^ 



to CU 
(1) ^ 

> B 

- (1) 
J-i 
O. 

a) 

4-1 w 

o 

00 
to "—I 
(U 

4J X) 
to 0) 

to 

<^ ^ 

to 



to 



to • 
0) to 

00 a) 
C --< 
to a. 

^1 @ 

to 
to 

'c ^ 

,-1 3 

E f-i 

to M-l 

to O 
u ^ 
fl. 
to pi 

1 o 

1-H 
•H to 

c 
o 
•i-i 



M-l 

o 



to 



to 



CO 6 

■-( 0) 

to J-i 

g tu 



J3 

to 

H 





H 


^ 


w 


<U 


CO^ 


•H 


4-1 


tu C 


3 


0) 


x; « 


!-i 


s 


u <u 


fn 


CO 


c e 




•H 


•H 



>. 




J3 


■u 




x: -CI 


(U 


bO^ c 


o 


•r^ 5-2 CO 


•H 


0) ^^ (U 


3 


IS B 


1^ 




O 


^ -vQ 


•i-l 


X t3 C 


j-i 


•r-l -H CO 


CO 


H tj OJ 


P< 


m to s 



•1-1 



•r4 

n 
pq 



to 

T) 
•H 
1—1 

o 
to 



XI 

3 



O 

H 



; to 

■' <u 
6 



X 

<L) 
S 



to 
o 

•H 

1— ( 

o. 
<u 
pc; 



ro 



<U 

s 

4-1 

to 

CU 
u 

H 



C4-I 


4-1 


o 


to 




<U 


(U 


> 


4-1 


W 


to 


to 



P X 



a- o 

E Z 



CO to CO to CO 



n in t3^ o vo 
lo in <)■ in <f 



CO to CO CO CO 



vo \o ro CO in 
in in in in <i- 



to to CO CO tO 



o o cN in tn 
vo vo >^ in m 



CM CM <N (N CS 



to to to to to 



in CM in r^ o 

CM f^ vO vO >^ 



CM CM CM CM CM 



CO CO to to CO 



00 CM CM in in 
<!■ r^ <f CM r^ 



CM IN CM CM <N 



to CO to to CO 



00 CM CM in o 
n O >.0 r^ e3^ 



CO CO CO to to 



in 00 00 CM GO 
vo CJ^ r^ in en 



CO tN CM (N C\l 

in in in in m 



00 CJ^ 00 CJ^ r-~ 

<t ■<)■ <i- vj- <^ 



en <!■ CM tN (N 

<J- <!■ <h <)• <i- 



00 r^ r^ oo<^ 
vt- -* •* •<t <!■ 



tOtOtOcQtO cOcOtflcO^ tOtOcOcOcO cOtOtOtOtO 

lnl-^o^^o<^ e^^r-iinom >^voi— ivoin i— looosoo 

oo^f-d-r^co tT>voinoo ooi— ii-ii— im <t\ CD en o r^ 

O^CT^C3^CJ^e3^ OOOi— lO i— iCMCMCMt-H (NrocsincM 

1— li— li— Ir— (i— I 1— <i-H,— li— li-H ,_|,_|,_(,_(,_| 

cOcOcflcflcO cOcOcOtOtO tOcOcOtOtfl tOtOcOcfltO 

* * * * 

vD<)-CMvd-n^-si— lOOOOCM^-N U-li— ICJ^CMCM^-^ OOOCOi— li— I/-N 

ooooooooooinoooor~-ooooin r^r^vor^r^in r-^vor-^r^t^m 

o oo oo oo o 

a 

^ o u ,n XI o J3 

tOXiOXaO tOxiOtOo tOcOxiWo cOcOcfltOtO 

^ * -Jc * * 

ini-Hin^<r/-NCMcNinocM^-> cMoomoom'-N cmoooocmcm^n 

•vteyir^i— ir^cM cri<tcM00cMO oomrovocMO i— icTiCTifOOr^ 

oo^^r^oor^o^oooooooooo^3^ oooooooooo<J^ cyioooocTicjNOO 

\^^ S_X N,^ ' 

oinininm unmininm ooooo ooooo 

CMa^vOl— ivD r^rOt-(\OrH 0OinrO>d-r-i OvOr^i— 100 

OOr^r-^OOr- OOOOOOOOOO OOOOOOOOOO tTiOOOOCJ>00 

ininminm mminmin ooooo ooooo 

vDcy>oocnr~ <fincMr^i-i mr-^r^ocM cMi— ii-i^r^ 

OOr^r^OOt^ OOOOOOOOOO OOOOOOCJ>00 CJ^O^CJ^O^00 

ininoino inininmin ooooo ooooo 

r^oor^or^ mcMcN^tcM oomoo-cj-n l-l<J^l-(CJ^cM 

oor^r^oor^ oooooooooo oooor^oooo cj>oocJNOOeri 

oooom ininininin ooooo ooooo 

cMONooooo ^7^lnmcon cMvovocy\vt cmcvioi — i- 

oor^r^cor-~ cT\oooo<y>oo onoooooooo a\ <3\ <y\ <y\ <y\ 



u O r\i vo i-H 

tu vo I CJ^ I 

x: I pis I cij 

U Pi M P-i pq 



u 

(U 
XI 

o 



O O CM vO 1-1 

(U \0 I ^J^ I 

x: I Pd I OS 

U Pi P3 PM pq 



u 

(U 



u 
o -d- 

vO 
\0 (Ti 



I 

> 

o 
la 






.^ 






^ 




o 


O CN vo 


i-l 


u 


O CM vO 1-1 


<u 


vo 1 a\ 


1 


<u 


vO 1 C?\ 1 


X 


1 Pi 1 


C^ 


X 


1 Pi 1 Pi 


u 


pti m P^ 


m 


U Pi PQ pLi pq 




u 






h 




<u 






« 




^ 










§ 






§ 




g 






u 

tu 




Z <f 






Q <)■ 




VO 






VO 




CM 0^ 






•< ty> 




1—1 I— 1 






r^ i-H 



«M 



CO 



CM 



O 



CO 
U 

3 
O 
X 

CM 



O 

IZ 



to 

o 



o 

14-1 



to 

.-I 

to 



o 

•H 
M 

to 
to 
60 

tu 
c 
tu 

o 

XX 



CU 



•1-1 o 
(U 

tu o 

(U is 

60 •- 
CD to 
13 U 

0) O 
^4 X 

tu 

> CM 

CO 

OJ -^ 

1-1 <r) 

i o 
CO 2 



•H to 

14-1 O 
X 
CU 



CU 
X 
4-1 

4J 

to 



c 

(U 
M 

(U 

14-t 
14-1 
•1-1 



O 

•H 
14-1 
•1-1 
C 
60 



4J 

o 
c 

0) 

)-l 

(U 

4J 



to 4J 

to 
0) CU 

X H 
4J 

>^ 60 
X C 

to 
TJ Pi 

(U 
^ (U 

Oi-i 
1-1 CL, 
1-1 •H 

O 4-1 
14-1 1-1 

"^ 

CU 
ti !* 

CO (U 

C to 
<U- 

> s 

•1-1 CO 

60 U 

_ C 

CO S 

Q 

C 

o o 



CO 
•O 

4-1 

to 
<u 
> 

X 

<u 

X 



CO 60 

6 ^ 

to .H 
CUT) 

E ^4 

o 

4-1 O 

^ y 

CU to 
B 

4J 1-1 

CO tu 
(U > 

M tu 

X 



^4 

o 

14-1 
73 

to 
•a 

c 

CO 



CO 
60 
CU 



s 

•1-1 

c 

•H 

s 
•x 



108 



9.5 



CO 

Q 
H 

O 
CO 

o 

CO 



H 
O 

H 

H 

U 
U 

Pi 
w 



9.0 



8.5 — 



rMinimum solids for fresh 
^shipment--color added 



8.0 




O Check 

A R-60 

a BR- 2 

P-96 

9 BR-1 



16 
October 



1 12 
November 



December 



DATE OF HARVEST 

Figure 20. Effect of 4 oils on soluble solids development in 'Hamlin' 
oranges. Sprays applied 18 September 1964. 



109 

indicates the approximate date by which the fruit in the various treat- 
ments attained the minimum legal solids requirement for color- added 
oranges, the category in which these 'Hamlin' oranges would have been 
placed. Again, the data for P-96 should be viewed with skepticism be- 
cause of faulty application of the oil spray. 

Discussion . --The data in Table 17 indicate that oil heaviness and 
possibly oil refinement are factors in the adverse effect of oil sprays 
on internal quality of citrus fruits. All oils significantly delayed 
solids development up through 6 weeks after application of the late- 
season spray. By the eighth week, the solids level in the fruit from 
the light-oil plots had risen to a level not significant from that of 
the check fruit. The solids levels of the fruit from the plots sprayed 
with the 70-SSU, low-refined oil and the 92-SSU, high-refined oil were 
still significantly below that of the check fruit. Although the dif- 
ferences between the 3 oils were not significant, the results unques- 
tionably favor the light oil, since it was associated with the least 
reduction in solids throughout the sampling period. By the time of the 
fourth sampling, reduction in solids by the oils was apparently overcome. 
Although the solids levels in the fruit from the sprayed plots were 
lower than that of the check, the differences were non- significant. 
The graph in Figure 20 indicates that the fruit sprayed with the light 
oil attained the minimum legal solids level approximately 1 week ear- 
lier than the fruit treated with the heavy oil and the low-refined oil. 

The reversal in solids development in the check fruit and those 
receiving the faulty application of the medium oil from the second to 
the third sampling dates is without explanation other than that it 
might be due to sampling error. The supply of fruit remaining on the 



110 

relatively small trees at the time of the third sampling prevented 
selection of the fruit with regard to fruit size and location on the 
tree, both of which are recognized (69) sources of error in sampling 
for fruit quality. However, this fruit supply limitation existed in 
the plots treated with the other oils as well. 

The adverse effect of oil sprays on citrus fruit quality has re- 
ceived much attention in both Florida (34, 67, 83, 89, 91) and 
California (51, 52, 53, 54, 66). The work in Florida has dealt mainly 
with timing of application without particular attention to the heavi- 
ness of the oil. Thompson and Sites (83) used both 72-SSU and 100-SSU 
oils in their experiments dealing with the timing of oil sprays. It 
is unlikely that beyond 70-SSU viscosity differences would occur with 
increase in oil heaviness. But the results discussed above indicate 
that oils lighter than 70 SSU might well have less adverse effect on 
fruit quality than the heavier oils. However, Riehl et al . (51) found 
no relationship between the molecular weight gradient of petroleum 
fractions in the range 200 to 350 and the effect of the oil on solids 
and acid in juice of 'Valencia' oranges in California, almost 1 year 
after spraying. Apparently the adverse effect of oil on solids is 
more prolonged under California conditions than under Florida condi- 
tions, because Thompson and Sites (83) reported very little adverse 
effect on solids of early, midseason, and late varieties of sweet 
oranges by oil sprays applied in June or July in Florida. The timing 
experiments of Thompson and Sites (83) and the results obtained in the 
present work suggest that the lighter, more volatile oils would have 
less adverse effect on fruit quality in Florida than the heavier oils 
which dissipate more slowly. 



Ill 

The increase in soluble solids in the fruit during the maturation 
period of citrus is directly dependent on the synthesis of the materi- 
als, mainly carbohydrates, by the leaves and subsequent translocation 
to the fruit. Any limitations imposed on either the synthesis or 
translocation of these products probably are reflected in the mature 
fruit in the form of reduced solids content. It seems likely that re- 
duction in total functional leaf surface, resulting from excessive leaf 
drop, and inhibition of photosynthesis in oil- sprayed leaves would both 
be limiting factors in solids development in the fruit. Wedding et al. 
(98) stated that the reduction of the soluble solids caused by oil 
sprays is probably due to an interference with the net production of 
photosynthate by the tree, or to a decrease in the translocation of 
elaborated foods from the leaves to the fruit, or to a combination of 
these factors. Wedding and Riehl (99) reported inhibition of phos- 
phorus translocation into leaves of oil- treated citrus plants and, on 
the basis of reduced ash content of the leaves, concluded that inhibi- 
tion of translocation was general and non-specific. Knight et al . 
(36) attributed starch build-up in oil-sprayed leaves to inhibition of 
outward translocation of carbohydrates from the treated leaves. 
Wedding and Riehl (99) stated the probability of physical interference 
with the transport system, especially since the highly refined oils are 
quite unreactive. They wrote: . ' 

"...it is probable that the effect on translocation comes 
about through a physical interference with the transport 
mechanism. This might be due to actual obstruction of the 
vessels with oil but it seems more reasonable to assume 
that the presence of oil partially disables translocation 
by altering interfacial tensions within the protoplasm or 
by changing the structure and molecular orientation of 
transport pathways within the protoplasm by 'solubiliza- 
tion' in its lipid phases." 



112 

Since the cells in oil- soaked leaf tissue are not killed, the duration 
of the effect of oil on these cellular and systemic functions is 
indirectly related to the dissipation rate of the oil deposit (57). 
Therefore, the lighter oils should have less over- all adverse effect 
on the citrus tree than the heavier, less volatile oils. 

General Discussion 

It is recognized (25, 48) that citrus trees in the more humid 
regions, as in Florida, are not as adversely affected by spray oils as 
in drier climates, such as that in California; and that heavier, and 
possibly less-refined, oils may be used with relative safety. The 
relative safety of the heavier oils is good from an entomological point 
of view because of the residual effectiveness of the less volatile oils; 
the less refined oils are of economic desirability because of their 
comparative low cost. However, the main problem associated with the 
use of oils on citrus in Florida is that of phytotoxicity and not in- 
secticidal efficiency. The screening data presented in Table 6 indi- 
cate that the majority of the oils currently used in Florida fall in 
the physical property range of maximum efficiency. The results of the 
other insecticidal and ovicidal efficiency studies reported herein sug- 
gest that paraffinic oils in the viscosity range of 55 to 60 SSU, or 
naphthenic oils of comparable distillation range, would render effi- 
cient pest control at currently recommended rates of application, es- 
pecially since biological control agents have effectively reduced the 
scale problem over the past few years (63, 64). 

The oils used on citrus in California are predominantly naphthenic 
and as such are considerably lower boiling, hence more volatile, than 
the paraffinic oils of comparable viscosity used in Florida. Yet these 



1 ,' 



113 

light oils have been highly successful in controlling insect and mite 
pests very similar to those affecting citrus in this state. The light- 
medium and medium grades (Table 1) of naphthenic oils widely used in 
California are approximately equivalent to 50- to 57-SSU paraffinic 
oils in distillation and volatility. If oils in this viscosity range 
can be used effectively in the pest control program on Florida citrus, 
the results obtained in these studies indicate that some of the phyto- 
toxic effects of oil would be alleviated. However, the residual pesti- 
cidal effectiveness of these lighter oils might not be as good as that 
of the 70- to 80-SSU oils currently used. This brings up the question 
of seasonal timing of applications with respect to oil heaviness to ob- 
tain the most effective pest control with minimum adverse effect to the 
tree. In early-season application, up to 15 July, when residual control 
is of greatest importance, oils of approximately 70 viscosity might 
exert sufficient residual control to carry over to the fall miticide 
spray. Thompson and Sites (83) showed that applications of oils of 72 
to 100 SSU had little adverse effect on fruit quality when applied be- 
fore 1 August. After 15 July, the lighter, more volatile oils probably 
would give effective pest control up to the time of the fall spray 
applications, with minimum phytotoxic effects, especially on early 
varieties. Applications of the lightest effective oils after 1 August 
might be feasible. 

Current recommendations caution growers against applying oil 
sprays after 1 August. The results of the fruit quality study dis- 
cussed above showed that the reduction of solids by the 60-SSU oil was 
overcome in 8 weeks after spraying. This indicates the possibility of 
applying these lighter oils up to 15 August or later without appreciable 



114 

effect on solids at the time of harvest after mid-October. This would 
be of great importance to growers with large acreages who sometimes 
find difficulty in completing their summer oil applications by the 
1 August deadline. However, extensive field testing is necessary be- 
fore recommendations for oil specifications can be presented. The 
specifications desired are those which combine full pesticidal effi- 
ciency with minimum phytotoxic effects. 



SUMMARY AND CONCLUSIONS 

Laboratory and field investigations were conducted to determine 
the relationship of certain physical and chemical properties of petro- 
leum oils to insecticidal and ovicidal efficiency and phytotoxicity to 
citrus under Florida conditions. Three series of narrow- boiling petro- 
leum fractions provided wide ranges of molecular weight (250 to 520) , 
viscosity (41 to 402 SSU) , 50% distillation temperature (581 to 911 F), 
and base type or composition (naphthenic, paraffinic, and reformed) for 
study. A large number of commercial oils were also available and were 
tested to a limited extent. 

The oils were formulated in the laboratory with an oil-soluble 
emulsifier. Laboratory applications were made with a laboratory air- 
blast sprayer similar in performance to commercial air-blast sprayers 
used in the field. Standard field application methods were used in 
field studies. Quantitative determinations of oil deposits were made 
by spectrophotometric methods, utilizing an oil- soluble indicator dye. 

Dosage-mortality tests were conducted in the laboratory against 
adult female Florida red scale on grapefruit and against citrus red 
mite eggs on immature 'Valencia' oranges. These infested fruit were 
sprayed with various concentrations of selected oils, sufficient to 
establish dosage-mortality relationships. The data were computer- 
analyzed by probit analysis to obtain the regression coefficient and 
LD5Q and LDg5 values and their 95% confidence limits for each oil. 

The LDg5 values for the oils in each series were plotted against 

increasing values of molecular weight, viscosity, and 507o distillation 



115 



116 

temperatures to illustrate the relation of these physical properties to 
insecticidal and ovicidal efficiency. The over- all relative efficiency 
of the 3 series of oils, in decreasing order, was reformed, paraffinic, 
and naphthenic. The optimum and minimum physical property values for 
scalicidal and (ovicidal) efficiency for the 3 series were: 

1) Molecular weight- -reformed, 305 and 279 (320 and 285 ); 
paraffinic, 305 and 291 (365 and 304 ) ; and naphthenic, 
320 and 300 (320 and 313) . 

2) Viscosity, SSU at 100 F--reformed, 59 and Sj. (66 and _52) ; 
paraffinic, 60 and _53 (99 and _6]^) ; and naphthenic, 80 and 
66 (80 and 25) . 

3) Fifty per cent distillation point--reformed, 700 F and 
644 F (716 F and 660 F ); naphthenic, 689 F and 657 F 
(689 F and 677 F ); and paraffinic, 696 F and 661 F 
(752 F and 694 F ) . 

The property values for maximum efficiency and the minimum property 

values for efficient kill were slightly lower for red scale than for 

citrus red mite eggs. However, oil deposits necessary for 95% kill of 

red scale were more than double those for the mite eggs, except with 

the lightest oils. These were more efficient against red scale than 

against mite eggs. Beyond the physical property values corresponding 

to maximum efficiency, efficiency declined with increase in heaviness 

of the oil. This reversal in effectiveness was more apparent for 

Florida red scale than for citrus red mite eggs. Thirty commercial 

oils, screened in the laboratory against Florida red scale, failed to 

show correlation between kill and increasing heaviness in the viscosity 

range of 57 to 112 SSU. Most of these oils fall within the efficient 

ranges for the physical properties considered. 



The minimum property value for efficiency is underlined; the 
property values for ovicidal efficiency are in parentheses. 



117 

The effects of various oils on the respiration and transpiration 
rates of potted 'Pineapple' seedlings were determined in the laboratory. 
At deposit levels comparable to those obtained in normal field applica- 
tions, paraffinic and naphthenic oils of 305 and 365 mol wt failed to 
affect respiration significantly. However, at twice the normal deposit 
level, the heavier paraffinic fraction caused significant reduction. 
The effect on transpiration rate was related to oil heaviness. Paraf- 
finic and naphthenic fractions of 285, 320, and 365 mol wt reduced 
transpiration significantly the first few days after treatment but the 
reduction was greatest for the 2 heavier fractions in each series. 
Rather rapid recovery was associated with the 2 light fractions and the 
320-mol wt naphthenic fraction but the 320-mol wt paraffinic and both 
365-mol wt fractions significantly inhibited transpiration throughout 
a 70-day period of measurement. Inspection of the physical property 
data of the oils indicated that the duration of the effect on transpi- 
ration was related more to distillation temperatures, hence volatility, 
than to any other property, either chemical or physical. Recovery by 
the treated plants accompanied dissipation of the oil deposit. 

Four commercial- type oils were field-tested to determine the re- 
lation of oil heaviness and refinement to phytotoxic effects. Early- 
season application failed to induce oil blotch although the fruit were 
in the most highly susceptible stage, 0.75 to 1.50 inches in diameter. 
However, considerable leaf and fruit drop followed this application and 
the extent of drop was apparently related inversely to oil heaviness 
and refinement. 

A late- season application of the same oils was made on the same 
trees to study the relation of oil type to adverse effect on degreening 



118 

rate and internal quality of fruit. Degreening rates were measured 
instrument ally and fruit quality determinations were made by standard 
methods. Fruit samples were harvested approximately 4, 6, 8, and 12 
weeks after spraying. 

Degreening rates were determined for the 4- and 8-week samples by 
measuring the color of the fruit after 0, 24, 48, and 72 hours of 
ethylene degreening. Fruit from oil- sprayed plots were significantly 
greener than the check fruit at the time of harvest and after degreen- 
ing at both 4 and 8 weeks after treatment. At 4 weeks, the check fruit 
degreened at a significantly higher rate than the treated fruit. How- 
ever, fruit sprayed with the light oils degreened at a significantly 
faster rate than those treated with the heavy oils, and these differ- 
ences were reflected in per cent pack-out of the fruit after 72 hours 
degreening. 

At 8 weeks after spraying, fruit from the oil- sprayed plots were 
still significantly greener than those from the check plots and the 
fruit treated with the heavy oil were significantly greener than those 
treated with the light oils. Fruit treated with the heavy oil showed 
no on-tree color break between the fourth and eighth weeks. However, 
the rates of degreening with ethylene gas at 8 weeks were greater for 
the oil-sprayed fruit than for the check fruit. Although the degreen- 
ing rates were faster for the oil-sprayed fruit, the rates were not 
sufficiently greater to overcome the on-tree color differences. All 
treated fruit, except that from the light-oil plots, was significantly 
greener after 72 hours degreening than the check fruit. However, these 
differences were not reflected in per cent pack-out. The over- all ad- 
verse effect of the oils was less with the light oil than with the heavy 
oil. 



119 

Internal fruit quality, as measured by per cent soluble solids in 
the juice, was determined at all 4 sampling dates. All oils delayed 
solids development to about the same extent up to 6 weeks after spray- 
ing. At 8 weeks, the solids content of the fruit sprayed with the heavy 
oil was still significantly lower than that of the check fruit but the 
fruit from the light- oil plots were not. By the twelfth week, no sig- 
nificant differences in solids were detected although the solids con- 
tent was still slightly lower in the sprayed than in the unsprayed 
fruit. The unsprayed fruit and the fruit sprayed with the light, 
highly-refined oil passed minimum legal maturity standards at an ear- 
lier date than did those treated with the heavy oil. 

On the basis of the results obtained in the studies discussed 
above, the following conclusions are drawn: 

1) Relatively little difference exists in insecticidal efficiency 
and phytotoxicity of oils of paraffinic and naphthenic composi- 
tion when compared on the basis of distillation temperatures 
rather than viscosity or molecular weight. 

2) The oils currently used in Florida fall in the effective and 
efficient range of physical property values. 

3) However, oils lighter than those currently used, in the vis- 
cosity range of 55 to 60 SSU, might be just as effective at the 
normal rates of application. .'* : 

4) The phytotoxic properties of highly refined petroleum oils are 
closely related to the heaviness of the oil and endurance of 
the oil deposit, and the extent and duration of phytotoxic 
effects are inversely related to the volatili4:y of the oil. 



120 



5) Therefore, the adverse effects of oil to Florida citrus could 
be alleviated by the use of the lightest insecticidally effi- 
cient oils. 
The combination of properties combining the least adverse effect 
to the citrus tree with efficient insect control can be determined only 
through extensive field testing. However, the results obtained in 
these studies point toward this combination of properties. They can 
serve as the basis for selecting candidate materials for field testing 
which may lead eventually to the recommendation of more rigid specifi- 
cations for oils used on citrus in Florida. 



LITERATURE CITED 



1. Abbott, W. S. 1925. A method of computing the effectiveness of an 

insecticide. J, Econ. Entomol. 18(2) :265-267 . 

2. Bartholomew, E. T., W. B. Sinclair, and E. C. Raby. 1934. Granu- 

lation (crystallization) of Valencia oranges. California Citro- 
graph 19:88-89, 106, 108. 

3. Burroughs, A. M. , and W. M. Grube. 1923. A simplified method for 

making lubricating oil emulsions. J. Econ. Entomol. 16(6): 534- 
539. 

4. Burroughs, A. M. 1923. Effects of oil sprays on fruit trees. 

Proc. Amer. Soc. Hort. Sci. 20:269-277. 

5. Chapman, P. J., G. W. Pearce, and A. W. Avens . 1941. The use of 

petroleum oils as insecticides. Ill: Oil deposits and the con- 
trol of the fruit tree leafroller and other apple pests. J. 
Econ. Entomol. 34(5) : 639- 647 . 

6. Chapman, P. J., G. W. Pearce, and A. W. Avens. 1943. Relation of 

composition to the efficiency of foliage or summer type petrole- 
um fractions. J. Econ. Entomol. 36 (2) :241-247 . 

7. Chapman, P. J, and G. W. Pearce. 1947. Oil sprays. Agr . Chem. 

2(3):17-20. 

8. Chapman, P. J. 1959. Tree spray oils-- their present status. New 

York State Agr. Exp. Sta. Farm Research 25(1) :7. 

9. Chapman, P. J., S. E. Lienk, A. W. Avens, and R. W. White. 1962. 

Selection of a plant spray oil combining full pesticidal ef- 
ficiency with minimum plant injury hazards. J. Econ. Entomol. 
55(5):737-744. 

10. Crafts, A. S., and H. G. Reiber. 1948. Herbicidal properties of 

oils. Hilgardia 18(2):77-156. 

11. Cressman, A. W. , and L. H. Dawsey. 1936. The comparative insecti- 

cidal efficiency against the camphor scale of spray oils with 
different unsulfonatable residues. J. Agr. Res. 52(11) :865-878. 

12. Dallyn, E. L., and R. D. Sweet. 1951. Theories on the herbicidal 

action of petroleum hydrocarbons. Proc. Amer. Soc, Hort. Sci. 
57:347-354. , > 



121 



^liip«»»"?"^ 



122 



13. Dallyn, E. L. 1953. Herbicidal action of oils. Cornell Agr . 

Exp. Sta. Memoir 316:1-43. 

14. Dean, H. A., and J. C. Bailey. 1961. Properties of spray oils 

for grapefruit in the Rio Grande Valley of Texas for 1961. J. 
Rio Grande Valley Hort. Soc. 15:10-11. 

15. Dean, H. A., and J. C. Bailey. 1963. Control of Texas citrus 

mites with various spray oil fractions. J. Rio Grande Valley 
Hort. Soc. 17:116-122. 

16. Dean, H. A., and J. C. Bailey. 1963. Responses of grapefruit 

trees to various spray oil fractions. J. Econ. Entomol. 56 
(5):547-551. 

17. Dean, H. A., E. L. Wilson, J. C. Bailey, R. W. White, and L. A. 

Riehl. 1964. A field technique for oil deposit determination 
on citrus through colorimetric analysis. J. Econ. Entomol. 
57(4):458-461. 

18. DeOng, E. R. 1926. Technical aspects of petroleum oils and oil 

sprays. J. Econ. Entomol. 19(5) : 733-745 . 

19. DeOng, E. R., H. Knight, and J. C. Chamberlin. 1927. A pre- 

liminary study of petroleum oil as an insecticide for citrus 
trees. Hilgardia 2(9) :351-384. 

20. Duncan, D. B. 1955. Multiple range and multiple F tests. 

Biometrics 11:1-42. 

21. Ebeling, W. 1932. Experiments with oil sprays used in the con- 

trol of the California red scale, Chrysomphalus aurantii 
(Maskell) (Homoptera: Coccidae) on lemons, J. Econ. Entomol. 
25(5):1007-1012. 

22. Ebeling, W. 1936. Effect of oil spray on California red scale 

at various stages of development, Hilgardia 10(4) :95-125 . 

23. Ebeling, W. 1945. Properties of petroleum oils in relation to 

toxicity to potato tuber moth larvae. J. Econ. Entomol. 38 
(l):26-34. 

24. Ebeling, W. 1950. Spray oils, p. 165-215. In W. Ebeling, Sub- 

tropical entomology. Lithotype Press Co., San Francisco. 

25. Ebeling, W. 1959. Spray oils, p. 57-66. In W. Ebeling, Sub- 

tropical fruit pests. Univ. California Div. Agr. Sci., Los 
Angeles . 

26. Finney, D. J. 1952. Probit analysis. Second edition. Cam- 

bridge Univ. Press, London. 318 p. 



123 



27. Fiori, B. J., E. H. Smith, and P. J. Chapman. 1963. Some factors 

influencing the ovicidal effectiveness of saturated petroleum 
oils and synthetic isoparaf f ins. J. Econ. Entomol. 56(6) :885- 
888. 

28. Ginsburg, J. M. 1931. Penetration of petroleum oils into plant 

tissue. J. Agr. Res. 43(5) :469-474. 

29. Gray, G. P., and E. R. DeOng . 1925. Laboratory and field tests 

of California petroleum insecticides. Ind~. Eng . Chem. 18:175- 
180. 

30. Green, J. R., and A. H. Johnson. 1931. Effect of petroleum oils 

on the respiration of bean leaves. Plant Physiol. 6:149-159. 

31. Green, J. R. 1936. Effect of petroleum oils on the respiration 

of bean plants, apple twigs and leaves, and barley seedlings. 
Plant Physiol. 11:101-113. 

32. Grierson, W., and W. F. Newhall. 1960. Degreening of Florida 

citrus fruits. Univ. Florida Agr. Exp. Sta. Bull. 620. 80 p. 

33. Grierson, W., M. F. Oberbacher, and W. L. Thompson. 1960. Fruit 

color, grove practices, and fresh fruit pack-out with particu- 
lar reference to tangerines. Proc. Florida State Hort. Soc. 
73:96-100. 

34. Harding, P. L. 1953. Effects of oil emulsion and parathion 

sprays on composition of early oranges. Proc. Amer . Soc. 
Hort. Sci. 61:281-285. 

35. Hubbard, H. G. 1885. Insects affecting the orange. U. S. 

Government Printing Office, Washington, D. C. 227 p. 

36. Knight, H., J. C. Chamberlin, and CD. Samuels. 1929. On 

some limiting factors in the use of saturated petroleum oils 
as insecticides. Plant Physiol. 4:299-321. 

37. McMillan, R. T., and J. M. Riedhart. 1964. The influence of 

hydrocarbons on photosynthesis of citrus leaves. Proc. 
Florida State Hort. Soc. In Press . 

38. Merrin, G. A. 1929. The effect of oil sprays on the transpi- 

ration of citrus. Proc. Florida State Hort. Soc. 42:219-224. 

39. Minshall, W. H., and V. A. Helson. 1949. Herbicidal action of 

oils. Proc. Amer. Soc. Hort. Sci. 53:294-298. 

40. Nelson, F. C. 1927. The penetration of a contact oil spray into 

the breathing system of an insect. J. Econ. Entomol. 20(4): 
632-635. 



>»■ 



124 



41. Oberle, G. D., G. W. Pearce, P. J. Chapman, and A. W. Avens . 

1944. Some physiological responses of deciduous fruit trees 
to petroleum oil sprays. Proc . Amer. Soc. Hort. Sci. 45: 
119-130. 

42. Pearce, G. W. , P. J. Chapman, and A. W. Avens. 1942. Efficiency 

of dormant type oils in relation to their composition. J. 
Econ. Entomol. 35(2) : 211-220 . 

43. Pearce, G. W., P. J. Chapman, and D. E. H. Frear. 1948. In- 

secticidal efficiency of saturated petroleum fractions. Ind . 
Eng. Chem. 40(2) :284-293 . 

44. Pearce, G. W., and P. J. Chapman. 1952. Insecticidal efficiency 

of petroleum fractions and synthetic isoparaf f ins . ^H ^S^i" 
cultural applications of petroleum products. Amer. Chem. Soc . j 
Washington, D. C. Advances in Chem. Ser. 7:12-14. 



45. Rhoads, W. A,, and R. T. Wedding, 
California Agr . 7(10) :9. 



1953. Leaf drop in citrus. 



46. Riedhart, J. M. 1961. Influence of petroleum oils on photo- 

synthesis of banana leaves. Trop. Agr. Trinidad. 38(1): 23-27. 

47. Riehl, L. A., and J. P. LaDue. 1952. Evaluation of petroleum 

fractions against California red scale and citrus red mite. 

In Agricultural application of petroleum products. Amer. Chem. 

Soc, Washington, D. C. Advances in Chem. Ser. 7:25-36. 

48. Riehl, L. A., and G. E. Carman. 1953. Narrow-cut petroleum 

fractions of naphthenic and paraffinic composition for control 
of California red scale. J. Econ. Entomol. 46(6) : 1007-1013 . 

49. Riehl, L. A., and L. R. Jeppson. 1953. Narrow-cut petroleum 

fractions of naphthenic and paraffinic composition for control 
of citrus red mite and citrus bud mite. J. Econ. Entomol. 46 
(6):1014-1020. 

50. Riehl, L. A., F. A. Gunther and R. L. Beier. 1953. Application 

of precision photoelectric colorimeter to determination of oil 
deposit on laboratory- sprayed grapefruit. J. Econ. Entomol. 
46(5):743-750. 



51. Riehl, L. A., E. T. Bartholomew, and J. P. LaDue. 1954. Effects 

of narrow-cut petroleum fractions of naphthenic and paraffinic 
composition on leaf drop and fruit juice quality of citrus. J, 
Econ. Entomol. 47(1): 107-113. 

52. Riehl, L. A., R. T. Wedding, and J. R. Rodriguez. 1956. Effect 

of oil spray application timing on juice quality, yield, and 
size of Valencia oranges in a southern California orchard. J. 
Econ. Entomol. 49(3) :376- 382 . 



125 



53. Riehl, L. A., and J. P. LaDue. 1957. Effects of oil spray and of 

variation in certain spray ingredients on juice quality of 
citrus fruits in California orchards, 1950-1953. J. Econ. 
Entomol. 50(2) : 197-204. 

54. Riehl, L. A., L. R. Jeppson, and R. T. Wedding. 1957. Effect 

of timing of oil spray application during the fall on juice 
quality and yield of lemons in two orchards in southern 
California. J. Econ. Entomol. 50(1): 74-76. 

55. Riehl, L. A., J. P. LaDue, and J. L. Rodriguez, Jr. 1958. Evalu- 

ation of representative California spray oils against citrus 
red mite and California red scale. J. Econ. Entomol. 51(2): 
193-195. 

56. Riehl, L. A., R. T. Wedding, J. P. LaDue, and J. L. Rodriguez, Jr. 

1958. Effect of a California spray oil on transpiration of 
citrus. J. Econ. Entomol. 51(3) :317-320 . 

57. Riehl, L. A., and R. T. Wedding. 1959. Relation of oil type, 

deposit, and soaking to effects of spray oils on photosynthesis 
in citrus leaves. J. Econ. Entomol. 52(l):88-94. 

58. Riehl, L. A., and R. T. Wedding. 1959. Effects of naphthenic and 

paraffinic petroleum fractions of comparable molecular weight 
on transpiration of Eureka lemon and Bearss lime plants. J. 
Econ. Entomol. 52(2) : 334-335. 

59. Riehl, L. A., and R. T. Wedding. 1959. Effects of naphthenic 

and paraffinic petroleum composition of a comparable molecular 
weight or viscosity on photosynthesis of Eureka lemon leaves. 
J. Econ. Entomol. 52(5) : 883-884. 

60. Rohrbaugh, P. W. 1934. Penetration and accumulation of petroleum 

spray oils in the leaves, twigs, and fruit of citrus trees. 
Plant Physiol. 9(4) : 699-730. 

61. Rohrbaugh, P. W. 1941. Physiological effects of petroleum oil 

sprays on citrus. J. Econ. Entomol. 34(6) :812-815 . 

62. Schroeder, R. A. 1936. The effect of some summer oil sprays 

upon the carbon dioxide absorption of apple leaves. Proc . Amer. 
Soc. Hort. Sci. 33:170-172. 

63. Simanton, W. A. 1960. The reduced status of purple scale as a 

citrus pest. Proc. Florida State Hort. Soc. 73:64-69. 



64, 



Simanton, W. A. 1963. Ecological survey of citrus pests and 

disorders. Univ. Florida Agr. Exp. Sta. Annu. Rep. p. 218-219. 



65. Simanton, W. A., and Kenneth Trammel. 1965. Design and per- 
formance of a laboratory air-blast sprayer. In press . 



126 



66. Sinclair, W. B., E. T. Bartholomew, and W. Ebeling. 1941. Com- 

parative effects of oil spray and hydrocyanic acid fumigation 
on the composition of orange fruits. J. Econ. Entomol. 34(6): 
821-829. 

67. Sites, J. W. 1947. Internal fruit quality as related to pro- 

duction practices. Proc . Florida State Hort. Soc . 60:55-62. 

68. Sites, J. W., and W. L. Thompson. 1948. Timing of oil sprays 

as related to fruit quality, scale control, coloring, and tree 
condition. The Citrus Ind . 29(4): 5- 9, 26. 

69. Sites, J. W. 1953. Some factors affecting the quality of citrus 

fruits. Univ. Florida Citrus Exp. Sta. Mimeo Rep. 54-7. 

70. Smith, E. H., and G. W. Pearce. 1948. The mode of action of 

petroleum oils as ovicides. J. Econ. Entomol. 41(2) : 173-180 . 

71. Smith, E. H. 1952. Tree spray oils. In Agricultural application 

of petroleum products. Amer . Chem. Soc, Washington, D. C. 
Advances in Chem. Ser. 7:3-11. 

72. Smith, R. H. 1932. The tank-mixture method of using oil spray. 

Univ. California Agr . Exp. Sta. Bull. 527. 86 p. 

73. Smith, R. H. 1932. Experiments with toxic substances in highly 

refined spray oils. J. Econ. Entomol. 25(5) : 988-990 . 

74. Snedecor, G. D. 1956. Statistical methods. Fifth edition. The 

Iowa State Univ. Press, Ames. 534 p. 

75. Soule, M. J., Jr., and F. P. Lawrence. 1959. What every citrus 

grower should know- -maturity tests for fresh fruit. Univ. 
Florida Agr. Ext. Serv. Cir. 191. 18 p. 

76. Stewart, W. S., and W. Ebeling. 1946. Preliminary results with 

the use of 2,4-dichlorophenoxyacetic acid as a spray-oil 
amendment. Bot. Gaz. 108:286-294. 

77. Stewart, W. S . , and L. A. Riehl. 1948. Addition of 2,4-D to oil 

sprays. California Citrograph 33(10) :456-458 . 

78. Stewart, W. S., and H. Z. Hield. 1950. Effects of 2,4-dichloro- 

phenoxyacetic acid and 2,4,5- trichlorophenoxyacetic acid on 
fruit drop, fruit production, and leaf drop of lemon trees. 
Proc. Amer. Soc. Hort. Sci. 55:163-171. 

79. Stewart, W. S., L. A. Riehl, and L. C. Erickson. 1952. Effects 

on citrus of 2,4-D used as an amendment to oil sprays. J. Econ. 
Entomol. 45(4) : 658- 668 . 



127 



80. Stofberg, F. J., and E. F. Anderssen. 1949. Effects of oil 

sprays on the yield and quality of navel and Valencia oranges. 
Union of South Africa Dept. Agr . Sci. Bull. 296:1-19. 

81. Swingle, H. S., and 0. I. Snapp. 1931. Petroleum oils and oil 

emulsions as insecticides, and their use against the San Jose 
scale on peach trees in the south. U. S. Dep. Agr. Tech. Bull. 
253. 48 p. 

82. Thompson, W. L. 1942. Some problems of control of scale insects 

on citrus. Proc . Florida State Hort. Soc , 55:51-59. 

83. Thompson, W. L., and J. W. Sites. 1945. Relationship of solids 

and ratio to the timing of oil sprays on citrus. Proc. 
Florida State Hort. Soc. 58:116-123. 

84. Thompson, W. L. 1948. Spray control for the control of mites and 

scale insects in Florida. Lower Rio Grande Valley Citrus and 
Vegetable Institute, Third Annu. Proc. p. 95-105. 

85. Thompson, W. L. 1949. The relationship of timing post-bloom 

sprays to certain fruit blemishes on oranges. The Citrus Ind. 
30(4):5-8, 18. 

86. Thompson, W. L., and J. T. Griffiths, Jr. 1949. Purple scale and 

Florida red scale as insect pests of citrus in Florida. Univ. 
Florida Agr. Exp. Sta. Bull. 462:33-36. 

87. Thompson, W. L., J. T. Griffiths, Jr., and J. W. Sites. 1950. A 

progress report on parathion as an insecticide for citrus trees 
in Florida. Citrus Mag. 12(9): 30-33. 

88. Thompson, W. L. 1951. Important mites attacking citrus and their 

control. Citrus Mag. 13(11) : 20-22 . 

89. Thompson, W. L., J. T. Griffiths, Jr., and J. W. Sites. 1951. A 

comparison of oil emulsion and parathion for the control of 
scale insects on citrus. Proc. Florida State Hort. Soc. 64: 
66-71. 

90. Thompson, W. L., R. B. Johnson, and J. W. Sites. 1954. The 

status of the purple mite and its control. Proc. Florida State 
Hort. Soc. 67:50-56. 

91. Thompson, W. L. and E. J. Deszyck. 1957. Phosphatic insecticides 

mixed with oil emulsions for scale control and their effect on 
fruit quality. Proc. Florida State Hort. Soc. 70:31-38. 

92. Thompson, W. L. 1959. Leaf drop following spray applications on 

citrus. Proc. Florida State Hort. Soc. 72:29-34. 

93. Thompson, W. L., R. F. Brooks, and M. F. Oberbacher. 1961. Re- 

sults of spray programs on tangerines in relation to scale con- 
trol and fruit color. Proc. Florida State Hort. Soc. 74:58-62. 



■NMIPl tL . I . 



128 



94. Tucker, R. P. 1936. Oil sprays: chemical properties of petro- 

leum oil unsaturates causing injury to foliage. Ind . Eng. 
Chem. 28:458-464. 

95. Turrell, F. M. 1946. Tables of surfaces and volumes of spheres 

and of prolate and oblate spheroids, and spheroidal coef- 
ficients. First edition. Univ. California Press, Berkeley 
and Los Angeles. 153 p. 

96. Van Overbeek, J., and R. Blondeau. Mode of action of phytotoxic 

oils. Weeds 3(l):55-65. 

97. Volck, W. H. 1903. Spraying with distillates. California Agr . 

Exp. Sta. Bull. 153. 31 p. 

98. Wedding, R. T., L. A, Riehl, and W. A. Rhoads. 1952. Effect of 

petroleum oil spray on photosynthesis and respiration in citrus 
leaves. Plant Physiol, 27 (2) : 269-278. 

99. Wedding, R. T., and L. A. Riehl. 1958. Influence of petroleum 

oil on the translocation of phosphorus in small lemon plants. 
Amer. J. Bot. 45(2) : 138-142 . 

100. Winston, J. R. 1942. Degreening of oranges affected by oil 

sprays. Proc . Florida State Hort. Soc. 55:42-45. 

101. Woglum, R. S. 1926. The use of oil spray on citrus trees. 

(abstract) J. Econ. Entomol. 19(5) : 732-733 . 

102. Woglum, R. S., and J. R. LaFollette. 1934. The double treat- 

ment for scale pests in California citrus orchards. J. Econ. 
Entomol. 27(5) : 978-980. • 

103. Yothers, W. W. 1911. Recent results of spraying experiments for 

the control of the whitefly on citrus. Proc. Florida State 
Hort. Soc. 24:53-59. .. , . _ 

104. Yothers, W. W. 1913. The effects of oil insecticides on citrus 

trees and fruits. J, Econ. Entomol. 6(2) : 161-164 . 

105. Yothers, W. W. 1918. Spraying for control of insects and mites 

attacking citrus trees in Florida. U. S. Dep. Agr. Farmers' 
Bull. 933. 38 p. 

106. Yothers, W. W. 1925. Cold process oil emulsions. J. Econ. 

Entomol. 18(3) : 545-546 . 

107. Yothers, W. W. and 0. C. McBride, 1929. The effects of oil 

sprays on the maturity of citrus fruits. Proc. Florida State 
Hort, Soc, 42:193-218, 

108. Young, P. A. 1935. Oil-mass theory of petroleum oil penetration 

into protoplasm. Amer. J. Bot. 22(l):l-8. 



129 



109. Young, P. A. 1941. Physiological and physical effects of spray 

oils on deciduous trees. J. Econ. Entomol . 34(6) : 838-844. 

110. Ziegler, L. W. 1939. The physiological effects of mineral oils 

on citrus. The Florida Entomol. 22(2): 21-30. 






130 



ADDITIONAL REFERENCES 



Calpouzos, L., T. Theis, C. M. Rivera, and C. Colberg. 1959. Studies 
on the action of oil in the control of Mycosphaerella musicola on 
banana leaves. Phytopathology 49(3) : 119-122 . 

Calpouzos, L., N. E. Delfel, C. Colberg, and T. Theis. 1961. Relation 
of petroleum oil composition to phytotoxicity and Sigatoka disease 
control on banana leaves. Phytopathology 51(5) :317-321 . 

Calpouzos, L., N. E. Delfel, C. Colberg, and T. Theis. 1961. Viscosi- 
ty of naphthenic and paraffinic spray oils in relation to phytotox- 
icity and Sigatoka disease control on banana leaves. Phytopathology 
51(8):528-531. 

Calpouzos, L., and C. Colberg. 1964. Importance of source of spray 
oils for Sigatoka disease control and phytotoxicity to banana leaves. 
Phytopathology 54(2) :235-236 . 

Dean, H. A., E. L. Wilson, J. C. Bailey, and L. A. Riehl. 1961. 
Fluorescent dye technique for studying distribution of spray oil 
deposit on citrus. J. Econ, Entomol . 54(2) :333- 340. 

Johnson, CM., and W. M. Hoskins. 1952. Relation of acids and per- 
oxides in spray oils to the respiration of sprayed bean leaves and 
the development of injury. Plant Physiol. 27:507-525. 

Thompson, W. L., J. R. King, and E. J. Deszyck. 1956. Progress report 
on greasy spot and its control. Proc . Florida State Hort. Soc. 69: 
98-104. 



131 



■ ■■ - BIOGRAPHICAL SKETCH 

Kenneth Trammel was born 30 October 1937, at Skipperville, 
Alabama. He obtained his elementary and secondary education at Frost- 
proof, Florida, and was graduated from Frostproof High School in June 
1956, In June 1960, he received the degree of Bachelor of Science in 
Agriculture from the University of Florida. In September 1960, he 
enrolled in the Graduate School of the University of Florida as a 
National Defense Education Act Fellow in the Department of Entomology. 
Since that time, he has pursued his work toward the degree of Doctor of 
Philosophy. He has been employed as a full-time assistant in entomology 
at the University of Florida Citrus Experiment Station, Lake Alfred, 
since May 1963. 

The author is married to the former Bessie Ellen Robinson. They 
have 3 sons, Kenny, Keith, and Kurtis. 

He is a member of the Entomological Society of America, the 
Florida Entomological Society, the Florida State Horticultural Society, 
Gamma Sigma Delta, and Alpha Zeta. 



This dissertation was prepared under the direction of the chairman 
of the candidate's supervisory committee and has been approved by all 
members of that committee. It was submitted to the Dean of the College 
of Agriculture and to the Graduate Council, and was approved as partial 
fulfillment of the requirements for the degree of Doctor of Philosophy. 

24 April 1965 ■ . . ■ . 




^^(.--Oean, College of Agriculture 



Dean, Graduate School 



Supervisory Committee: 







ACRi- 

CULTURAL 

LIBRARY 



-.'' J i -/JL JJl... 



va 



UNIVERSITY OF FLORIDA 



3 1262 08554 8500 



'■)X\m